mid-15c., cohercen, from Middle French cohercer, from Latin coercere "to control, restrain, shut up together," from com- "together" (see co-) + arcere "to enclose, confine, contain, ward off," from PIE *ark- "to hold, contain, guard" (see arcane). Related: Coerced; coercing. No record of the word between late 15c. and mid-17c.; its reappearance 1650s is perhaps a back-formation from coercion.