'non-Buddhist' is formed from the prefix 'non-' (from Latin 'non', meaning 'not') attached to 'Buddhist' (from 'Buddha', Sanskrit 'Buddha', with English agent-forming suffix '-ist', denoting an adherent).

'Buddhist' entered English in the 19th century from 'Buddha' (Sanskrit), with the suffix '-ist' forming a noun meaning 'follower of Buddha'. The compound 'non-Buddhist' is a Modern English formation using the negative prefix 'non-' to indicate negation of that affiliation.

Initially the elements meant 'not' + 'follower of Buddha'; the combined form has retained that literal sense and is used to describe either people or things not associated with Buddhism.