Hungarian word semmi comes from Hungarian mi, Hungarian sem (Neither.)

Detailed word origin of semmi

Dictionary entry	Language	Definition
mi	Hungarian (hun)	(personal) we (interrogative) what? (poetic) how ...!, what a ...! Mi, a syllable used in solfège to represent the third note of a major scale.
sem	Hungarian (hun)	Neither.
semmi	Hungarian (hun)	Nothing.

Words with the same origin as semmi