Wiktionary
electrofuge
n. (context chemistry English) A leaving group that does not carry away the bonding electron pair
Wikipedia
Electrofuge
An electrofuge is a leaving group which does not retain the bonding pair of electrons from its previous bond with another species. It can result from the heterolytic breaking of covalent bonds. After this reaction an electrofuge may possess either a positive or a neutral charge; this is governed by the nature of the specific reaction.
An example would be the loss of H from a molecule of benzene during nitration.
The word 'electrofuge' is commonly found in older literature, but its use is now uncommon.