"in a sloping direction, not permendicular or at right angles," early 14c., o-slant, literally "on slant," from a- (1) "on" + slant (v.). As a preposition from c. 1600.
the sun shone aslant into his face
ask
askance
asker
askew
asking
aslant
asleep
Asmodeus
asocial
asp
asparagus