“+- noun
Etymology: trichlor- + phenoxy- + acetic
: a crystalline irritating compound Cl 3 C 6 H 2 OCH 2 COOH resembling dichlorophenoxyacetic acid, made from the corresponding trichloro-phenol and chloroacetic acid, and used chiefly in the form of esters as a weed killer especially for woody plants — usually used with initial numbers
2,4,5-trichlorophenoxyacetic acid
— called also 2,4,5-T