structure vs understructure

structure and understructure both are nouns.

Word	Noun	Adjective	Verb	Adverb
structure	Yes	No	Yes	No
understructure	Yes	No	No	No

structure (noun)	understructure (noun)
a thing constructed; a complex entity constructed of many parts	lowest support of a structure
the manner of construction of something and the arrangement of its parts
a particular complex anatomical part of a living thing and its construction and arrangement
the complex composition of knowledge as elements and their combinations
the people in a society considered as a system organized by a characteristic pattern of relationships

structure (verb)	understructure (verb)
give a structure to