Prince is a general term for a ruler, monarch or member of a monarch's or former monarch's family, and is a hereditary title in the nobility of some European states. The feminine equivalent is a princess. The English word derives, via the French word prince, from the Latin noun princeps, from primus (first) + capio (to seize), meaning "the chief, most distinguished, ruler, prince".
Commonly, prince refers to a male member of a royal family, especially, a son of the sovereign.
The original, but now less common, use of the word, originated in the application of the Latin word princeps, from Roman, more precisely Byzantine law, and the classical system of government that was 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).
Currently, the husband of a queen regnant is usually titled prince or prince consort, whereas the wives of male monarchs take the female equivalent of their husbands' title—the same as is used when a female mounts the throne in her own right, such as empress or queen. In Brazil, Spain and Portugal, however, the husband of a female monarch was accorded the masculine equivalent of her title—at least after she bore him a child. In previous epochs, husbands of queens regnant often shared their consorts' regnal title and rank.