A snare was a type of trap.
Chief Engineer Geordi La Forge found himself in a snare of the Pakled. He was beamed aboard their ship the Mondor to assist in necessary repairs and was then held prisoner to "make them stronger" by increasing their weapons power. (TNG: "Samaritan Snare")
When the USS Enterprise-D suffered from a major power loss following investigations about a Promellian battle cruiser, Captain Picard assumed that the Enterprise-D fell into the same snare as the Promellians, a thousand year old booby trap. (TNG: "Booby Trap").