The Spanish verb 'estilar' comes from the Latin word 'stillare', meaning 'to drip'. The Latin word was combined with the Spanish infinitive verb suffix '-ar' to form 'estilar'. While it retained its original meaning of 'to drip', it also developed the figurative meaning 'to be customary' - similar to how we might say in English that something 'trickles down' to become common practice.

A related Spanish word is 'estilizar' meaning 'to stylize', though this follows a slightly different etymological path through the word 'estilo' (style). The connection between liquid dropping and style comes from the ancient writing implement called a stylus, which was used to make marks by flowing ink.

English speakers might recognize the connection to words like 'distill' and 'instill', which both come from the same Latin root 'stillare'. 'Distill' refers to the process of purifying liquids through dripping, while 'instill' metaphorically means to gradually introduce ideas or qualities - as if dripping them into someone's mind.