Is “Onto” a Scrabble word?
Yes
ONTO
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 Onto
/ˈɒn.tuː/
adjective
1.(of a function) Assuming each of the values in its codomain; having its range equal to its codomain.
“Considered as a function on the real numbers, the exponential function is not onto.”
Synonyms: surjective
preposition
1.Upon; on top of.
“My cat just jumped onto the keyboard.”
2.Aware of.
“The thought-police were onto my plans of world domination.”
3.Being an onto function with a codomain of (see below).
“The exponential function maps the set of real numbers onto the set of positive real numbers.”