nombril vs midpoint

nombril and midpoint both are nouns.

Word	Noun	Adjective	Verb	Adverb
nombril	Yes	No	No	No
midpoint	Yes	No	No	No

As nouns, midpoint is a hypernym of nombril; that is, midpoint is a word with a broader meaning than nombril:

nombril: the center point on a shield
midpoint: a point equidistant from the ends of a line or the extremities of a figure

Other hypernyms of nombril include center, centre.

nombril (noun)	midpoint (noun)
the center point on a shield	a point equidistant from the ends of a line or the extremities of a figure