From Middle Englishclum, clom(“silence”), perhaps for *clomen(“stiff, numb”), past participle of *cleomen("to be stiff"; compare Middle Englishacleomen(“to be stiff”)), related to Middle Englishclumsen, clomsen(“to be stiff, be numb”), Dutchkleumen(“to be stiff from cold”); or perhaps representing Old Englishclom, clam, clamm(“band, bond, fetter, chain, grip, grasp”). Compare also Old Englishclumian(“to mutter”). More at clam.