'Underpart' definitions:
Definition of 'underpart'
From: WordNet
noun
A part lying on the lower side or underneath an animal's body; "the warbler has a white throat and underparts"; "a woodland mouse with white underparts"
Definition of 'Underpart'
From: GCIDE
- Underpart \Un"der*part`\, n. A subordinate part. [1913 Webster]
- It should be lightened with underparts of mirth. --Dryden. [1913 Webster]