WordNet sense 1 (without a basis in reason or fact):

baseless, groundless, unfounded, unwarranted, wild

WordNet sense 2 (not sustained or maintained by nonmaterial aid):

unsupported

WordNet sense 3 (be idle; exist in a changeless situation):

laze, slug, stagnate

WordNet sense 4 (silly or trivial):

light

WordNet sense 5 (not serious in content or attitude or behavior):

frivolous

WordNet sense 6 (lacking a sense of restraint or responsibility):

loose

WordNet sense 7 (showing lack of care for consequences):

irresponsible

WordNet sense 8 (not yielding a return):

dead

WordNet sense 9 (producing little or no profit or gain):

unprofitable

WordNet sense 10 (run disconnected or idle):

tick over

WordNet sense 11 (not having a job):

jobless, out of work

WordNet sense 12 (not engaged in a gainful occupation):

unemployed

WordNet sense 13 (idle or indolent especially in a dreamy way):

lackadaisical

WordNet sense 14 (disinclined to work or exertion):

indolent, lazy, slothful

WordNet sense 15 (not in active use):

unused

WordNet sense 16 (lacking activity; lying idle or unused):

inactive