- adrift
- afloat
- alternating
- amorphous
- capricious
- changeable
- changeful
- desultory
- deviable
- dizzy
- eccentric
- erratic
- fast and loose
- fickle
- fitful
- flickering
- flighty
- flitting
- fluctuating
- fly-by-night
- frail
- freakish
- fugitive
- giddy
- impetuous
- impulsive
- inconsistent
- inconstant
- indecisive
- infirm
- insubstantial
- irregular
- irresolute
- irresponsible
- mazy
- mercurial
- moody
- mutable
- rambling
- restless
- roving
- scatterbrained
- shapeless
- shifting
- shifty
- shuffling
- spasmodic
- spineless
- temporary
- transient
- transitory
- unaccountable
- uncertain
- uncontrolled
- undependable
- undisciplined
- unfixed
- unpredictable
- unreliable
- unrestrained
- unsettled
- unstable
- unstable as water
- unstaid
- unsteadfast
- unsteady
- unsure
- vacillating
- vagrant
- variable
- vicissitudinary
- vicissitudinous
- volatile
- wandering
- wanton
- wavering
- wavery
- wavy
- wayward
- whimsical
- wishy-washy