To vote for, increasing a cumulative tally of popularity.(verb)
A vote for something that increases a cumulative tally of popularity.(noun)
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Use "upvote" in a sentence
"Upboat or Upgoat - Another way of saying 'upvote'."
"Watch the video and pass it on - post it to Facebook, tweet it, blog it, talk about it, upvote it on Reddit - and join me today in standing for an impartial Supreme Court at ConflictedClarenceThomas.com."
"I volunteered in Miami yesterday to put upvote door hangers and today to shuttle people to polls."