Dictionary definitions that start with: O (3,640 entries)

on that point
on the alert
on the average
on the books
on the button
on the coattails
on the contrary
on the dot
on the face of it
on the far side
on the fence
on the fly
on the go
on the hook
on the job
on the loose
on the nose
on the offensive
on the one hand
on the other hand
on the q.t.
on the qt
on the qui vive
on the quiet
on the road
on the side
on the sly
on the spot
on the spur of the moment
on the table
BTW, Why won't you become an editor?