constrain 9 Associations

stiffen tighten tighten up restrict (generic term) restrain (generic term) trammel (generic term) limit (generic term)

loosen 6 Associations

loose change (generic term) alter (generic term) modify (generic term) stiffen (antonym)

loosen 6 Associations

relax loose weaken (generic term) stiffen (antonym)

petrify 7 Associations

rigidify ossify stiffen (generic term)

relax 5 Associations

loosen loose weaken (generic term) stiffen (antonym)