Emily Dickinson Lexicon

FIT, n. [Qu. W. fith, a gliding or darting motion. The French express the sense of this word by boutade, from bout, the primary sense of which is to shoot or push out. It seems to be allied to L. peto, impeto, to assault, or to Eng. pet, and primarily to denote a rushing on or attack, or a start. See Fit, suitable.]

1. The invasion, exacerbation or paroxysm of a disease. We apply the word to the return of an ague, after intermission; as, a cold fit. We apply it to the first attack, or to the return of other diseases; as, a fit of the gout or stone: and in general, to a disease however continued; as, a fit of sickness.
2. A sudden and violent attack of disorder, in which the body is often convulsed, and sometimes senseless; as, a fit of apoplexy or epilepsy; hysteric fits.
3. Any short return after intermission; a turn; a period or interval. He moves by fits and starts. By fits my swelling grief appears. Addison.
4. A temporary affection or attack; as, a fit of melancholy, or of grief; a fit of pleasure.
5. Disorder; distemperature. Shak.
6. [Sax. fitt, a song.] Anciently, a song, or part of a song, a strain; a canto. Lye. Johnson.