General:
* Anxiety: This is a broader term encompassing worry and unease.
* Apprehension: This refers to a feeling of dread or fear about something.
* Jitters: This is a more informal term for feeling anxious or uneasy.
Specific:
* Fidgeting: This is a physical manifestation of nervousness.
* Trembling: This refers to shaking or trembling due to nerves.
* Hesitation: This refers to pausing or delaying due to nervousness.
Metaphorical:
* Butterflies: A common idiom for nervousness.
* Knot: This refers to a feeling of tightness in the stomach, often associated with nerves.
Ultimately, the best noun for "nervous" depends on the specific situation and the nuance you want to convey.