WordNet sense 1 (not tense or taut):

slack

WordNet sense 2 (not taut or rigid; not stretched or held tight):

lax

WordNet sense 3 (grant freedom to; free from confinement):

liberate, release, unloose, unloosen, release

WordNet sense 4 ((of textures) full of small openings or gaps):

open

WordNet sense 5 (of textures that are rough to the touch or substances consisting of relatively large particles):

harsh

WordNet sense 6 (not firm or firmly fixed; likely to fail or give way):

insecure

WordNet sense 7 (lacking a sense of restraint or responsibility):

idle

WordNet sense 8 (not packaged or put into packets):

unpackaged

WordNet sense 9 (not officially recognized or controlled):

informal

WordNet sense 10 (not having official authority or sanction):

unofficial

WordNet sense 11 (not fitting closely; hanging loosely):

baggy, sloppy

WordNet sense 12 (turn loose or free from restraint):

unleash, let loose

WordNet sense 13 (characterized by phlegm):

phlegmy

WordNet sense 14 (having escaped, especially from confinement):

escaped, on the loose

WordNet sense 15 (able to act at will; not hampered; not under compulsion or restraint):

free

WordNet sense 16 (not literal):

liberal

WordNet sense 17 (not constipated):

regular, unconstipated

WordNet sense 18 (not being under control; out of control):

uncontrolled

WordNet sense 19 ((used of soil) loose and large-grained in consistency):

light

WordNet sense 20 (make loose or looser):

loosen

WordNet sense 21 (become loose or looser or less tight):

relax

WordNet sense 22 (casual and unrestrained in sexual behavior):

easy, promiscuous, sluttish, wanton

WordNet sense 23 (not chaste):

unchaste

WordNet sense 24 (not secured within a cover):

unbound

WordNet sense 25 (not affixed):

unaffixed