The Spanish word 'loca' (meaning 'crazy' in its feminine form) has an interesting Arabic origin. It comes from the Hispano-Arabic word '*láwqa', which meant 'stupid' (feminine form). This word can be traced back to Classical Arabic 'lawqa'', also meaning 'stupid' (feminine), which in turn derives from the masculine form 'alwaq' meaning 'stupid'.

This etymology shows the strong influence of Arabic on Spanish vocabulary during the centuries of Muslim presence in the Iberian Peninsula. The meaning evolved slightly from 'stupid' to 'crazy', while maintaining its feminine form throughout its development.

The masculine form 'loco' is the more basic form of this word in Spanish, and you'll often see both forms used frequently in Spanish conversation and literature. Related words include 'locura' (craziness), 'enloquecer' (to drive crazy), and 'alocado/a' (wild, reckless).

While there aren't direct English cognates from this Arabic root, English speakers might find it helpful to remember 'loca' through popular cultural references like the phrase 'la vida loca' (the crazy life), which entered English through Latin music and pop culture, particularly Ricky Martin's hit song 'Livin' La Vida Loca'.