fit (n.1)

1680s, "process of fitting," from fit (v.). From 1823 as "the fitting of one thing to another;" 1831 as "the way something fits."

fit (n.2)

"paroxysm, sudden attack" (as of anger), 1540s, probably via Middle English sense of "painful, exciting experience" (early 14c.), from Old English fitt "conflict, struggle," which is of uncertain origin, with no clear cognates outside English. Perhaps ultimately cognate with fit (adj.) on notion of "to meet." Meaning "sudden impulse toward activity or effort" is from 1580s. Phrase by fits and starts first attested 1610s (by fits is from 1580s).

fit (adj.)

"suited to the circumstances, proper," mid-15c., of unknown origin, perhaps from Middle English noun fit "an adversary of equal power" (mid-13c.), which is perhaps connected to fit (n.1). In athletics, "in condition, properly trained for action," from 1869. Related: Fitter; fittest. Survival of the fittest (1867) coined by H. Spencer.

fit (v.)

c. 1400, "to marshal or deploy (troops);" early 15c. as "be fitting or proper, be suitable," from fit (adj.) and perhaps in part from Scandinavian (compare Old Norse fitja "knit"). From 1580s as "be the right shape." Transitive sense of "provide with what is suitable" is from 1590s; that of "make fit or suitable, bring into corresponding form or condition" is from c. 1600. Related: Fitted; fitting. Fitted sheets is attested from 1948.

fit (n.3)

part of a poem, Old English fitt, of unknown origin; perhaps related to fit (n.2).

Definitions of fit
fit (v.)
be agreeable or acceptable to;
Synonyms: suit / accommodate
fit (v.)
be the right size or shape; fit correctly or as desired;
This piece won't fit into the puzzle
Synonyms: go
fit (v.)
make fit;
fit a dress
fit (v.)
insert or adjust several objects or people;
Can you fit the toy into the box?
This man can't fit himself into our work environment
fit (v.)
be compatible, similar or consistent; coincide in their characteristics;
Synonyms: match / correspond / check / jibe / gibe / tally / agree
fit (v.)
conform to some shape or size;
How does this shirt fit?
fit (v.)
provide with (something) usually for a specific purpose;
Synonyms: equip / fit out / outfit
fit (v.)
fill, satisfy or meet a want or need or condtion ro restriction;
Synonyms: conform to / meet / satisfy / fill / fulfill / fulfil
fit (v.)
make correspond or harmonize;
Synonyms: match
fit (n.)
a display of bad temper;
he had a fit
Synonyms: tantrum / scene / conniption
fit (n.)
a sudden uncontrollable attack;
a fit of coughing
Synonyms: paroxysm / convulsion
fit (n.)
the manner in which something fits;
I admired the fit of her coat
fit (n.)
a sudden flurry of activity (often for no obvious reason);
a fit of housecleaning
Synonyms: burst
fit (adj.)
(usually followed by `to' or `for') on the point of or strongly disposed;
she was fit to scream
laughing fit to burst
fit to drop
in no fit state to continue
Synonyms: primed / set
fit (adj.)
meeting adequate standards for a purpose;
a fit subject for discussion
it is fit and proper that you be there
water fit to drink
do as you see fit to
fit for duty
fit (adj.)
physically and mentally sound or healthy;
keeps fit with diet and exercise
felt relaxed and fit after their holiday