The Collaborative International Dictionary of English v.0.48:
Canvass \Can"vass\, v. t. [imp. & p. p. canvassed; p. pr. &
vb. n. Canvassing.] [OF. Canabasser to examine curiously,
to search or sift out; properly, to sift through canvas. See
1. To sift; to strain; to examine thoroughly; to scrutinize;
as, to canvass the votes cast at an election; to canvass a
district with reference to its probable vote.
I have made careful search on all hands, and
canvassed the matter with all possible diligence.
2. To examine by discussion; to debate.
An opinion that we are likely soon to canvass. --Sir
3. To go through, with personal solicitation or public
addresses; as, to canvass a district for votes; to canvass
a city for subscriptions.