A matchmaker was somebody who conspired to bring people together romantically.
In 2371, Kasidy Yates attributed Jake Sisko's speaking to his father often about her to Jake's trying to be a matchmaker. (DS9: "Family Business")
In 2372, when Jake suggested the couple spend three days in the Bajoran outback without him, saying he thought they'd have a better time without him, Benjamin told him to stop matchmaking. Jake clarified that he actually wanted to spend more time on his writing. (DS9: "The Muse")
In 2375, when Tom Paris encouraged Tuvok to pursue a relationship with Noss – given that USS Voyager might not rescue Paris and Tuvok and therefore the Vulcan might never see his wife again – Tuvok rejected Tom's attempt at "play(ing) matchmaker", as he was not in pon farr. (VOY: "Gravity")