'entristecer' originates from Spanish, formed by the prefix 'en-' (from Latin 'in-' used causatively), combined with 'triste' (from Latin 'tristis' meaning 'sad'), plus the verb-forming suffix '-ecer' (from Latin '-escere').

'entristecer' developed in Old Spanish as forms like 'entristeçer' built on 'triste' (from Latin 'tristis'); over time the orthography and pronunciation regularized into modern Spanish 'entristecer'.

Initially it was primarily an inchoative verb meaning 'to become sad'; over time it has also been used transitively to mean 'to make (someone) sad', and has produced related nouns and adjectives.