mid-15c., cohercen, "restrain or constrain by force of law or authority," from Old French cohercier, from Latin coercere "to control, restrain, shut up together," from assimilated form of com- "together" (see co-) + arcere "to enclose, confine, contain, ward off," from PIE *ark- "to hold, contain, guard" (see arcane). The unetymological -h- was perhaps by influence of cohere. Related: Coerced; coercing. No record of the word between late 15c. and mid-17c.; its reappearance 1650s is perhaps a back-formation from coercion.