Word: onsies
Part of speech: Noun
Syllables: on
sies
Definition: Plural of onsie; may mean

Onesie (jumpsuit), adult jumpsuit for relaxing or sleeping
Onesie (infant bodysuit), a garment worn by babies
Knucklebones, a children's game, is also called onesies
Morphemes:
Affix: onsie
Language: en
PoS: Noun
Meaning: Alternative form of onesie.
Affix: -s
Language: en
PoS: Suffix
Meaning: Used to form many pluralia tantum (nouns that are almost or entirely without singular forms).