means feeling anxious, tense, or easily agitated, often with a physical edge of jitters or unease.

from From Latin nervosus, 'sinewy, full of nerves,' from nervus, 'sinew, tendon, nerve' — itself a cousin of Greek neuron, 'sinew.' For centuries 'nervous' actually meant strong and vigorous (full of sinew); only later, as 'nerves' came to mean the body's wiring and the seat of agitation, did the word swing toward its modern jittery sense — strength of fiber giving way to fragility of feeling.