The Spanish word 'princesita' meaning 'little princess' comes from the Spanish word 'princesa' (princess) combined with the diminutive suffix '-ita'. The word 'princesa' itself came into Spanish through Old French 'princesse', which was the feminine form of 'prince'. Going further back, the French terms derived from the Latin word 'princeps', meaning 'first' or 'chief', which was used to refer to the leading citizen or ruler in ancient Rome.

The most obvious related Spanish word is 'princesa' (princess), from which 'princesita' is directly formed. Another common related word is 'príncipe' (prince). The diminutive suffix '-ita' is extremely common in Spanish and is used to form affectionate diminutives of many words, like 'perrita' (little dog) from 'perra' or 'casita' (little house) from 'casa'.

English speakers can easily relate 'princesita' to the English words 'prince' and 'princess', which share the same Latin ancestor 'princeps'. The English word 'principal' also comes from this Latin root, reflecting the original meaning of 'first' or 'chief' - think of a school principal as the chief administrator. Other related English words include 'principle' and 'primitive', all carrying some sense of being first or fundamental.