In a twitching or involuntarily jerking state; trembling or spasming slightly.
From 'a-' (in a state of) + 'twitch' (involuntary movement). 'Twitch' may derive from Middle English, possibly Germanic in origin.
This archaic adjective captures a nervous, fidgety quality—something constantly atwitch suggests instability, fear, or electrical impulses, which is why it shows up in Gothic and nervous literature.
Complete word intelligence in one call. Free tier — 50 lookups/day.