means the jittery, unsettled state of feeling anxious or apprehensive, often before something uncertain or important.

from From 'nervous,' which traces back to Latin 'nervosus' (sinewy, vigorous), from 'nervus' — a sinew, tendon, or cord, a cousin of Greek 'neuron.' Curiously, 'nervous' once meant strong and full of vigor (think of a 'nervous' style of writing — taut and muscular). Only later, as physicians began linking the body's literal 'nerves' to agitation and weakness of feeling, did the word twist toward today's meaning of anxious unease. The '-ness' is the plain old English suffix for turning a quality into a state of being.