The Spanish verb 'cuidar' (meaning 'to care for' or 'to look after') comes from the Old Spanish 'coidar' meaning 'to think' or 'to care', which in turn derives from the Latin verb 'cogitare' meaning 'to think'. The semantic evolution from 'thinking' to 'caring' makes intuitive sense, as caring for someone or something involves keeping them in mind and being thoughtful about their needs. The phonetic development from Latin 'cogitare' to modern Spanish 'cuidar' shows typical sound changes, with the medial 'g' being lost and the 'oi' eventually becoming 'ui'.

A related Spanish word is 'descuidar' meaning 'to neglect' or 'to be careless', which is formed by adding the negative prefix 'des-' to 'cuidar'. Another related word is 'cuidado' which can mean both 'care' as a noun and 'careful' as an adjective, as well as being used as a warning meaning 'careful!' or 'watch out!'

While not immediately obvious, the English word 'cogitate' (meaning 'to think deeply about something') is related to Spanish 'cuidar', as it also comes from Latin 'cogitare'. Other English derivatives include 'cogitation' (the act of thinking) and 'cogitative' (relating to thinking). While the Spanish word evolved to focus on the aspect of caring and looking after, the English cognates maintained the original meaning of thinking and contemplation.