leaving group; nucleofuge
Technical term in organic chemistry for the atom or group that departs with a pair of electrons in a heterolytic bond cleavage.
Halide ions are good leaving groups.
In this reaction, water is released as a leaving group.
脱離反応 (elimination reaction) is a reaction type where a leaving group is removed, often forming a double bond.
Compound of 脱離 (elimination, detachment) and 基 (group, radical). A calque from English 'leaving group'.