skittish

Synonyms: agitable alarmable capricious changeable combustible dizzy edgy excitable excited fearful fickle fidgety flighty frivolous giddy harebrained highstrung irresponsible jumpy lightheaded lively peppy playful restive scatterbrained sensitive spirited undependable unreliable volative whimsical zippy

Antonyms: calm collected easy-going laid-back unworried