n.
Pronunciation: ' ə l-tr ə - ˌ str ə k-ch ə r
Function: noun
Date: 1939
: biological structure and especially fine structure (as of a cell) not visible through an ordinary microscope
– ul · tra · struc · tur · al \ ˌ ə l-tr ə - ' str ə k-ch ə -r ə l, - ' str ə k-shr ə l \ adjective
– ul · tra · struc · tur · al · ly adverb