Meaning 1:
Transmission. An abbreviation.
Meaning 2:
For polymers, a prefix denoting a type of molecular structure. To some unsaturated carbon chain atoms within a mer unit, a single side atom or group may be situated on one side of the chain or directly opposite at a 180 rotation position. In a trans structure, two such side groups within the same mer reside on opposite chain sides (e.g, trans-isoprene).