The Latin word pr?nceps (older Latin *pr?smo-kaps, literally "the one who takes the first "), became the usual title of the informal leader of the Roman senate some centuries before the transition to empire, the princeps senatus.

Emperor Augustus established the formal position of monarch on the basis of principate, not dominion. He also tasked his grandsons as summer rulers of the city when most of the government were on holiday in the country or attending religious rituals, and, for that task, granted them the title of princeps.

The title has generic and substantive meanings:

• generically, prince refers to a member of a family that ruled by hereditary right, the title referring either to sovereigns or to cadets of a sovereign's family. The term may be broadly used of persons in various cultures, continents or eras. In Europe, it is the title legally borne by dynastic cadets in monarchies, and borne by courtesy by members of formerly reigning dynasties.
• as a substantive title, a prince was a monarch of the lowest rank in post-Napoleonic Europe, e.g. Princes of, respectively, Andorra, Hohenzollern-Sigmaringen, Mingrelia, Monaco, Waldeck and Pyrmont, Wallachia, etc.
• also substantively, the title was granted by popes and secular monarchs to specific individuals and to the heads of some high-ranking European families who, however, never exercised dynastic sovereignty and whose cadets are not entitled to share the princely title, viz the Princes de Beauvau-Craon, von Bismarck, Colonna, von Dohna-Schlobitten, von Eulenburg, de Faucigny-Lucinge, von Lichnowsky, von Pless, Ruffo di Calabria, (de Talleyrand) von Sagan, van Ursel, etc.
• generically, cadets of some non-sovereign families whose head bears the non-dynastic title of prince (or, less commonly, duke) were sometimes also authorized to use the princely title, e.g. von Carolath-Beuthen, de Broglie, Demidoff di San Donato, Lieven, de Merode, Pignatelli, Radziwill, von Wrede, Yussopov, etc.
• substantively, the heirs apparent in some monarchies use a specific princely title associated with a territory within the monarch's realm, e.g. the Princes of, respectively, Asturias (Spain), Grão Pará (Brazil, formerly), Orange (Netherlands), Viana (Navarre, formerly), Wales (UK), etc.
• substantively, it became the fashion from the 17th century for the heirs apparent of the leading ducal families to assume a princely title, associated with a seigneurie in the family's possession. These titles were borne by courtesy and preserved by tradition, not law, e.g. the princes de, respectively, Bidache (Gramont), Marcillac (La Rochefoucauld), Tonnay-Charente (Mortemart), Poix (Noailles), Léon (Rohan-Chabot),

The original, but now less common use of the word, originated in the application of the Latin word princeps, from late Roman law, and the classical system of government that eventually gave way to the European feudal society. In this sense, a prince is a ruler of a territory which is sovereign, or quasi-sovereign, i.e., exercising substantial (though not all) prerogatives associated with monarchs of independent nations, as was common, for instance, within the historical boundaries of the Holy Roman Empire. In medieval and Early Modern Europe, there were as many as two hundred such territories, especially in Italy, Germany, and Gaelic Ireland. In this sense, "prince" is used of any and all rulers, regardless of actual title or precise rank. This is the Renaissance use of the term found in Niccolò Machiavelli's famous work, Il Principe.

As a title, by the end of the medieval era, prince was borne by rulers of territories that were either substantially smaller than or exercised fewer of the rights of sovereignty than did emperors and kings. A lord of even a quite small territory might come to be referred to as a prince before the 13th century, either from translations of a native title into the Latin princeps (as for the hereditary ruler of Wales), or when the lord's territory was allodial. The lord of an allodium owned his lands and exercised prerogatives over the subjects in his territory absolutely, owing no feudal homage or duty as a vassal to a liege lord, nor being subject to any higher jurisdiction. Most small territories designated as principalities during feudal eras were allodial, e.g. the Princedom of Dombes.

Lords who exercised lawful authority over territories and people within a feudal hierarchy were also sometimes regarded as princes in the general sense, especially if they held the rank of count or higher. This is attested in some surviving styles for e.g., British earls, marquesses, and dukes are still addressed by the Crown on ceremonial occasions as high and noble princes (cf. Royal and noble styles).

In parts of the Holy Roman Empire in which primogeniture did not prevail (e.g., Germany), all legitimate agnates had an equal right to the family's hereditary titles. While this meant that offices, such as emperor, king, and elector could only be legally occupied by one dynast at a time, holders of such other titles as duke, margrave, landgrave, count palatine, and prince could only differentiate themselves by adding the name of their appanage to the family's original title. Not only did this tend to proliferate unwieldy titles (e.g. Princess Katherine of Anhalt-Zerbst, or Karl, Count Palatine of Zweibrücken-Neukastell-Kleeburg, or Prince Christian Charles of Schleswig-Holstein-Sonderburg-Plön-Norburg), but as agnatic primogeniture gradually became the norm in the Holy Roman Empire by the end of the 18th century, another means of distinguishing the monarch from other members of his dynasty became necessary. Gradual substitution of the title of Prinz for the monarch's title of Fürst occurred, and became customary for cadets in all German dynasties except in the grand duchies of Mecklenburg and Oldenburg. Both Prinz and Fürst are translated into English as "prince", but they reflect not only different but mutually exclusive concepts.

This distinction had evolved before the 18th century (Liechtenstein long remained an exception, cadets and females using Fürst/Fürstin into the 19th century) for dynasties headed by a Fürst in Germany. The custom spread through the Continent to such an extent that a renowned imperial general who belonged to a cadet branch of a reigning ducal family, remains best known to history by the generic dynastic title, "Prince Eugene of Savoy". Note that the princely title was used as a prefix to his Christian name, which also became customary.

Cadets of France's other princes étrangers affected similar usage under the Bourbon kings. Always facing the scepticism of Saint-Simon and like-minded courtiers, these quasi-royal aristocrats' assumption of the princely title as a personal, rather than territorial, designation encountered some resistance. In writing Histoire Genealogique et Chonologique, Père Anselme accepts that, by the end of the 17th century, the heir apparent to the House of La Tour d'Auvergne's sovereign duchy bears the title, prince de Bouillon, but he would record in 1728 that the heir's La Tour cousin, the Count of Oliergues, is "known as the Prince Frederick" ("dit le prince Frédéric").

The post-medieval rank of gefürsteter Graf (princely count) embraced but elevated the German equivalent of the intermediate French, English and Spanish nobles. In the Holy Roman Empire, these nobles rose to dynastic status by preserving from the Imperial crown (de jure after the Peace of Westphalia in 1648) the exercise of such sovereign prerogatives as the minting of money; the muster of military troops and the right to wage war and contract treaties; local judicial authority and constabular enforcement; and the habit of inter-marrying with sovereign dynasties. By the 19th century, cadets of a Fürst would become known as Prinzen.

The husband of a queen regnant is usually titled "prince consort" or simply "prince", whereas the wives of male monarchs take the female equivalent (e.g., empress, queen) of their husband's title. In Brazil, Portugal and Spain, however, the husband of a female monarch was accorded the masculine equivalent of her title (e.g., emperor, king), at least after he fathered her heir. In previous epochs, husbands of queens regnant were often deemed entitled to the crown matrimonial, sharing their consorts' regnal title and rank jure uxoris,

However, in cultures which allow the ruler to have several wives (e.g., four in Islam) and/or official concubines (e.g., Imperial China, Ottoman Empire, Thailand, KwaZulu-Natal) these women, sometimes collectively referred to as a harem, there are often specific rules determining their relative hierarchy and a variety of titles, which may distinguish between those whose offspring can be in line for the succession or not, or specifically who is mother to the heir to the throne.

To complicate matters, the style His/Her (Imperial/Royal) Highness, a prefix often accompanying the title of a dynastic prince, may be awarded/withheld separately (as a compromise or consolation prize, in some sense, e.g., Duke of Cádiz, Duchess of Windsor, Princesse de Réthy, Prince d'Orléans-Braganza).

Although the arrangement set out above is the one that is most commonly understood, there are also different systems. Depending on country, epoch, and translation, other usages of "prince" are possible.

Foreign-language titles such as Italian principe, French prince, German Fürst and Prinz (non-reigning descendants of a reigning monarch), Russian knyaz, etc., are usually translated as "prince" in English.

Some princely titles are derived from those of national rulers, such as tsarevich from tsar. Other examples are (e)mirza(da), khanzada, nawabzada, sahibzada, shahzada, sultanzada (all using the Persian patronymic suffix -zada, meaning "son, descendant"). However, some princely titles develop in unusual ways, such as adoption of a style for dynasts which is not pegged to the ruler's title, but rather continues an old tradition (e.g., "grand duke" in Romanov Russia or "archduke" in Habsburg Austria), claims dynastic succession to a lost monarchy (e.g. prince de Tarente for the La Trémoïlle heirs to the Neapolitan throne, or descends from a ruler whose princely title or sovereign status was not, de jure, hereditary, but attributed to descendants as an international courtesy, (e.g., Bibesco, Poniatowski, Ypsilanti).

Specific titles

In some dynasties, a specific style other than prince has become customary for dynasts, such as fils de France in the House of Capet, and Infante. Infante was borne by children of the monarch other than the heir apparent in all of the Iberian monarchies. Some monarchies used a specific princely title for their heirs, such as Prince of Asturias in Spain and Prince of Brazil in Portugal.

Sometimes a specific title is commonly used by various dynasties in a region, e.g. Mian in various of the Punjabi princely Hill States (lower Himalayan region in British India).

European dynasties usually awarded appanages to princes of the blood, typically attached to a feudal noble title, such as Prince of Orange in the Netherlands, Britain's royal dukes, the Dauphin in France, the Count of Flanders in Belgium, and the Count of Syracuse in Sicily. Sometimes appanage titles were princely, e.g. Prince of Achaia (Courtenay), prince de Condé (Bourbon), Prince of Carignan (Savoy), but it was the fact that their owners were of princely rank rather than that they held a princely title which was the source of their pre-eminence.

For the often specific terminology concerning an heir apparent, see Crown prince.

Other princes derive their title not from dynastic membership as such, but from inheritance of a title named for a specific and historical territory. The family's possession of prerogatives or properties in that territory might be long past