Tetryon plasma

From Memory Alpha, the free Star Trek reference

Tetryon plasma is a variety of warp plasma.

In 2372 in an alternate timeline, Lieutenant Lasca asked Harry Kim to explain a dilithium fracture problem related to the tetryon plasma in the USS Yellowstone's warp nacelles, but Kim didn't know the answer and feigned sickness to get away with his apparent ignorance.

A vessel equipped with normal warp drive can stall out when passing through a cloud of tetryon plasma. (VOY: "Non Sequitur")