Definitions for onto-
Random House Webster's College Dictionary
on•toˈɒn tu, ˈɔn-; unstressed ˈɒn tə, ˈɔn-(prep.)
to a place or position on; upon; on.
Informal. aware of the true nature, motive, or meaning of:
I'm onto your tricks.
(adj.)Math. pertaining to a function or map from one set to another set, the range of which is the entire second set.
Origin of onto:
a combining form meaning “being”:
Origin of onto-:
< NL < Gk
Origin: from ὤν present participle of εἰμί