Onto
来自Big Physics
wiktionary
From on + to, after into. Compare Saterland Frisian antou(“up to”).
etymonline
onto (prep.)
"toward and upon; to and in connection with; to the top of," 1580s, on to, from on + to. It appeared much later than parallel into, unto. As a closed compound, onto (on analogy of into), it is recorded from 1715. "The word is regarded by purists as vulgar, and is avoided by careful writers" [Century Dictionary, 1895].
