adj.
likely to change frequently often without apparent or cogent reason; variable; "inconstant affections"; "an inconstant lover"; "swear not by...the inconstant moon"- Shakespeare
adj.
capable of replacing or changing places with something else; permitting mutual substitution without loss of function or suitability; "interchangeable electric outlets" "interchangeable parts"
adj.
liable to sudden unpredictable change; "erratic behavior"; "fickle weather"; "mercurial twists of temperament"; "a quicksilver character, cool and willful at one moment, utterly fragile the next"
adj.
inclined to shake as from weakness or defect; "a rickety table"; "a wobbly chair with shaky legs"; "the ladder felt a little wobbly"; "the bridge still stands though one of the arches is wonky"
adj.
incapable of failure or error; "an infallible antidote"; "an infallible memory"; "the Catholic Church considers the Pope infallible"; "no doctor is infallible"