undependable (adj.)
- adrift
- afloat
- alternating
- amorphous
- capricious
- changeable
- changeful
- coquettish
- dangerous
- desultory
- dizzy
- doubtful
- dubious
- eccentric
- erratic
- faddish
- fickle
- fitful
- flickering
- flighty
- flirtatious
- fluctuating
- fly-by-night
- freakish
- giddy
- hazardous
- impetuous
- impulsive
- inconsistent
- inconstant
- indecisive
- infirm
- insecure
- insubstantial
- irregular
- irresolute
- irresponsible
- light
- mazy
- mercurial
- moody
- perilous
- precarious
- provisional
- quicksilver
- rambling
- restless
- risky
- rocky
- roving
- scatterbrained
- shaky
- shapeless
- shifting
- shifty
- skittish
- slippery
- spasmodic
- spineless
- temporary
- tentative
- ticklish
- tottery
- treacherous
- tricky
- unaccountable
- uncertain
- uncontrolled
- undisciplined
- unfixed
- unhealthy
- unpredictable
- unreliable
- unrestrained
- unsafe
- unsettled
- unsound
- unstable
- unsteady
- unsubstantial
- unsure
- untrustworthy
- untrusty
- vacillating
- vagrant
- variable
- versatile
- volatile
- wandering
- wanton
- wavering
- wavy
- wayward
- whimsical
- wishy-washy
