(a.) Having abundance of mettle; ardent; full of fire; as, a high-mettled steed.

agitable all nerves antsy antsy-pantsy anxious apprehensive breathless chafing combustible eager emotional emotionally unstable eruptive excitable excited explosive fearful fretful fretting frightened hasty high-mettled high-spirited high-strung highly emotional hopped-up impatient impetuous in a lather in a stew in a sweat inflammable irascible irritable mettlesome nerves on edge nervous nervy on edge overstrung panicky perturbable prickly restive restless sensitive skittery skittish squirming squirmy startlish touchy uneasy unpatient unquiet uptight volatile volcanic