/tran'speuh ray"sheuhn/ , n.
1. an action or instance of transpiring.
2. Bot. the passage of water through a plant from the roots through the vascular system to the atmosphere.
[ 1545-55; TRANS- + L spiration-, s. of spiratio breathing ( spirat ( us ), ptp. of spirare to breathe + -ion- -ION); perh. directly ]