The Spanish interrogative pronoun 'qué' (meaning 'what') comes from Old Spanish 'que', which in turn derives from the Latin word 'quid', also meaning 'what'. The evolution from Latin 'quid' to modern Spanish 'qué' shows a typical pattern of phonological simplification, where the final '-d' was lost, and the modern Spanish form maintains the interrogative accent mark to distinguish it from the relative pronoun 'que'.

The unaccented Spanish word 'que' is closely related to 'qué'. While 'qué' is used as an interrogative pronoun ('what?'), 'que' serves as a relative pronoun ('that', 'which') or conjunction. Both words share the same Latin ancestry, though they developed slightly different functions in modern Spanish.

While English 'what' is not directly related to Spanish 'qué' (as 'what' comes from Germanic origins), English has many words derived from the same Latin interrogative root, particularly in formal or academic vocabulary. For example, 'query' (to ask a question), 'quest' (a search or inquiry), and 'question' itself all share a distant relationship with 'qué' through their Latin origins in the interrogative stem 'qu-'.