inert, indifferent, neutral - having only a limited ability to react chemically; not active; "inert matter"; "an indifferent chemical in a reaction" Antonym:reactive (indirect, via unreactive)
inert, sluggish, torpid - slow and apathetic; "she was fat and inert"; "a sluggish worker"; "a mind grown torpid in old age" Antonym:active (indirect, via inactive)