A twit is a foolish person. (It's also not any kind of goldfish.) It's most often used in the expression "to feel a bit of a twit". Another common usage is as a substitute for the word "twat" when you realise mid-sentence that you are talking to a vicar / primary school teacher / the Pope / etc.

Twit is mainly used today for its comedy value, as it is possibly the most ineffectual insult in the English language.

Roald Dahl once wrote a book called The Twits, which painted some people with the surname Twit in a very bad light.

TO TWIT

To reproach a person, or remind him of favours conferred.

The 1811 Dictionary of the Vulgar Tongue.

Twit (?), v. t. [imp. & p. p. Twitted; p. pr. & vb. n. Twitting.] [OE. atwiten, AS. aetwitan to reproach, blame; aet at + witan to reproach, blame; originally, to observe, see, hence, to observe what is wrong (cf. the meanings of E. animadvert; akin to G. verweisen to censure, OHG. firwizan, Goth. traweitan to avenge, L. videre to see. See Vision, Wit.]

To vex by bringing to notice, or reminding of, a fault, defect, misfortune, or the like; to revile; to reproach; to upbraid; to taunt; as, he twitted his friend of falsehood.

This these scoffers twitted the Christian with. Tillotson.

Aesop minds men of their errors, without twitting them for what is amiss. L'Estrange.

 

© Webster 1913.