n. & v.
--n.
1. a an extortion of payment in return for not disclosing discreditable information, a secret, etc. b any payment extorted in this way.
2 the use of threats or moral pressure.
--v.tr.
1. extort or try to extort money etc. from (a person) by blackmail.
2 threaten, coerce.
Derivatives:
blackmailer n.
Etymology: BLACK + obs. mail rent, OE mal f. ON m{aacute}l agreement