prep.
Pronunciation: ' o ̇ n-( ˌ )tü, ' än-
Function: preposition
Date: 1581
1 : to a position on
2 : in or into a state of awareness about <put me onto your methods>
3 ― used as a function word to indicate a set each element of which is the image of at least one element of another set <a function mapping the set S onto the set T >