Is “Oncer” a Scrabble word?
Yes
ONCER
Valid in at least one Scrabble dictionary
Valid in these dictionaries
SOWPODS / CSW
Scrabble UK & International
TWL / NWL
Scrabble North America
Large English Dictionary
General English word list
Meaning of Oncer
/ˈwʌnsə/
noun
1.A one-pound note.
2.A person who does something once.
3.A single sexual encounter between two individuals, a one-night stand.