Etymology
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habit (n.)

early 13c., "characteristic attire of a religious or clerical order," from Old French habit, abit "clothing, (ecclesiastical) habit; conduct" (12c.), from Latin habitus "condition, demeanor, appearance, dress," originally past participle of habere "to have, hold, possess; wear; find oneself, be situated; consider, think, reason, have in mind; manage, keep," from PIE root *ghabh- "to give or receive."

Habit is a custom continued so steadily as to develop a tendency or inclination, physical or moral, to keep it up; as, the habit of early rising; the habit of smoking. Habit and practice apply more often to the acts of an individual; fashion and usage more often to many .... [Century Dictionary]

Meaning "clothing generally" is from late 14c. Meaning "customary practice, usual mode of action" is early 14c. Drug sense is from 1887. The Latin word was applied to both inner and outer states of being, and both senses were taken in English, though meaning of "dress" now is restricted to monks and nuns. In 19c. it also was used of the costume worn by women when riding on horseback.

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habit (v.)
mid-14c., "to dwell, reside; dwell in" (obsolete), from Old French habiter, abiter "to dwell, inhabit; have dealings with," from Latin habitare "to live, dwell; stay, remain," frequentative of habere "to have, to hold, possess" (from PIE root *ghabh- "to give or receive"). Meaning "to dress" is from 1580s. Related: Habited; habiting.
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habiliment (n.)

often habiliments, early 15c., ablement, "munitions, weapons," from Old French habillement, abillement, from abiller "prepare or fit out," probably from abile, habile "fit, suitable," from Latin habilem, habilis "easily handled, apt," verbal adjective from habere "to hold" (from PIE root *ghabh- "to give or receive"). An alternative etymology [Barnhart, Klein] makes the French verb originally mean "reduce a tree by stripping off the branches," from a- "to" + bille "stick of wood." Sense of "clothing, dress" developed late 15c., by association with habit (n.).

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*ghabh- 
also *ghebh-, Proto-Indo-European root meaning "to give or receive." The basic sense of the root probably is "to hold," which can be either in offering or in taking.

It forms all or part of: able; avoirdupois; binnacle; cohabit; cohabitation; debenture; debit; debt; dishabille; due; duty; endeavor; exhibit; exhibition; forgive; gavel; gift; give; habeas corpus; habiliment; habit; habitable; habitant; habitat; habitation; habitual; habituate; habituation; habitude; habitue; inhabit; inhibit; inhibition; malady; prebend; prohibit; prohibition; provender.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit gabhasti- "hand, forearm;" Latin habere "to have, hold, possess," habitus "condition, demeanor, appearance, dress;" Old Irish gaibim "I take, hold, I have," gabal "act of taking;" Lithuanian gabana "armful," gabenti "to remove;" Gothic gabei "riches;" Old English giefan, Old Norse gefa "to give."
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flaunt (n.)
1620s, "act or habit of flaunting," from flaunt (v.).
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lisp (n.)
"act or habit of lisping," 1620s, from lisp (v.).
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self-indulgence (n.)

"habit of undue gratification of one's own passions, desires, etc.," 1650s; see self- + indulgence.

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thew (n.)
Old English þeaw "usage, custom, habit;" see thews.
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habitude (n.)

"customary manner, habit," c. 1400, from Old French habitude (14c.), from Latin habitudinem (nominative habitudo) "condition, appearance, habit," noun of state from past-participle stem of habere "have, hold; manage, keep" (from PIE root *ghabh- "to give or receive"). Related: Habitudinal (late 14c.).

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thews (n.)
Old English þeawes "customs, habit, manners; morals, conduct, disposition, personal qualities," plural of þeaw "habit, custom," from Proto-Germanic *thawaz (source also of Old Saxon thau "usage, custom, habit," Old High German thau "discipline"). According to OED, with no certain cognates outside West Germanic and of unknown origin. Meaning "bodily powers or parts indicating strength, good physique" is attested from 1560s, from notion of "good qualities." Acquired a sense of "muscular development" when it was revived by Scott (1818).
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