means A female member of a royal family, typically the daughter of a king or queen, or a woman married to a prince.

from From the Latin 'princeps,' meaning 'first, chief, leader' — literally the one who 'takes first place' (primus + capere, 'to take'). This gave us 'prince,' and the feminine 'princess' arrived in English in the late 14th century by way of Old French 'princesse.' So beneath the tiara lies a word that simply meant 'the one who comes first' — fitting, perhaps, for someone used to going to the front of the line.