1. Easily excited or irritated.
  2. Of or relating to the nerves.
  3. Originating in or affected by the nerves.
  4. Tending to produce nervousness or agitation.
  5. Easily agitated or alarmed; tending to be anxious; highly strung.
  6. A feeling or reaction resulting from anxiety or anticipation.

The emotion of Nervousness is found in the Small Intestine meridian in the Fire element

Definitons from Dictionary by Merriam-Webster and Oxford Dictionary.