Wiktionary
a. (context idiomatic English) undecided; wavering in one's opinion
WordNet
adj. characterized by indecision; "some who had been on the fence came out in favor of the plan"; "too many voters still declare they are undecided" [syn: on the fence(p), undecided]
Usage examples of "on the fence".
A boy and a girl about my age are leaning on the fence, chatting, and I look down on the prettiest, cleanest pigs Ive ever seen.
I didn't move, and I'm sure Wolfe didn't, so it must have been our friend on the fence-maybe he jumped off into the pasture.
Grendels must learn from other grendels: there hadn't been another mass assault on the fence.
He turned only once to stare at Chaney hanging on the fence and then raced away along the tracks.
While I held the ring and let the light play on it, the accused, with his left hand, beat a lively little dance rhythm on the fence.
There were about thirty strands on the fence, with roughly six inches between each pair.
Roland surmised he had thought of a way to turn the number written on the fence into an actual place.
He crouched, waiting, ready to leap up on the fence, the sightlines beneath the lower branches relatively clear.
He took a high grip on the fence with his right, raised his right foot as high as he could and pointed his shoe into one of the diamond-shaped openings in the fence.