1610s, "something stored up," from reserve (v.) or from French réserve, a back-formation from reserver "set aside, withhold," from Latin reservare "keep back, save up; retain, preserve," from re- "back" (see re-) + servare "to keep, save, preserve, protect" (from PIE root *ser- (1) "to protect").

Meaning "self-imposed restraint on freedom of words or actions; habit of keeping back the feelings" is from 1650s. The meaning "district or place set apart for some particular use" is by 1805. The sense of "amount of capital kept on hand to meet probable expenses or demand" is by 1866. That of "amount of natural resources known to exist in a particular region" is by 1912. As an adjective, "kept in reserve," by 1719.

The military sense of "body of troops withheld from action to serve as reinforcements, etc." is from 1640s; that of "national emergency defense or auxiliary military force" (reserves) is by 1866.

late 14c., "act of reserving or keeping back," from Old French reservation (14c.) and directly from Late Latin reservationem (nominative reservatio), noun of action from past-participle stem of Latin reservare "keep back, save up; retain, preserve," from re- "back" (see re-) + servare "to keep, save, preserve, protect" (from PIE root *ser- (1) "to protect").

The mental sense of "qualification of a statement, etc., not expressed openly" is from c. 1600. The U.S. sense of "tract of public land set aside for some special use," especially exclusive use by native peoples, is from 1789, in reference to the Six Nations in New York State. The meaning "act or fact of engaging a room, a seat, etc." is from 1904, also originally American English.

1680s, "a place where something tends to collect, place where anything is kept in store," originally figurative, from French réservoir "storehouse," from Old French reserver "set aside, withhold," from Latin reservare "keep back, save up; retain, preserve," from re- "back" (see re-) + servare "to keep, save, preserve, protect" (from PIE root *ser- (1) "to protect").

Specific meaning "capacious artificial basin to collect and store water" is from 1705. Earlier in this sense, and more common late 17c.-early 18c., was reservatory (1660s). Meaning "part of a machinery in which fluid is contained" is by 1784.

late 14c., "to check, restrain (sin, error); to overcome, put down, subdue (riot, rebellion);" from Latin repressus, past participle of reprimere "hold back, curb," figuratively "check, confine, restrain, refrain," from re- "back" (see re-) + premere "to press, hold fast, cover, crowd, compress" (from PIE root *per- (4) "to strike").

Used of feelings or desires from late 14c.; in the purely psychological sense "keep out of the conscious mind, keep in the subconscious" it represents German verdrängen (Freud, 1893), that sense of the word first attested in English in 1904 (implied in repressed). Related: Repressed; repressing.

also ischaemia, 1866 (but as far back as 1660s in form ischaimes), from medical Latin ischaemia, from ischaemus "stopping blood," from Greek iskhaimos "stanching or stopping blood," from iskhein "to hold, curb, keep back, restrain" (from PIE *si-sgh-, reduplication of root *segh- "to hold" (from PIE root *segh- "to hold") + haima "blood" (see -emia). Related: Ischemic.

mid-14c., "forbearance in indulgence of the appetites," from Old French abstinance (earlier astenance), from Latin abstinentia "abstinence, starvation; self-restraint, integrity," abstract noun from abstinentem (nominative abstinens), present participle of abstinere/abstenere "withhold, keep back, keep off," from assimilated form of ab "off, away from" (see ab-) + tenere "to hold" (from PIE root *ten- "to stretch"). Especially of sexual appetites but also in Middle English of food, fighting, luxury.

mid-14c., refreinen, transitive, "exercise control over, restrain; hold (someone or something) back from action," senses now obsolete, also "exercise control over" (thoughts, desires, feelings, vices, etc.); from Old French refraigner, refrener, refreiner "restrain, repress, keep in check" (12c., Modern French réfréner).

This is from Latin refrenare "to bridle, hold in with a bit, check, curb, keep down, control," from re- "back" (see re-) + frenare "restrain, furnish with a bridle," from frenum "a bridle," a word of uncertain etymology (de Vaan supports a theory that it is connected to fretus "relying on").

The classical spelling was restored in French but not in English. In Middle English chiefly transitive. Intransitive sense of "forbear, keep oneself (from)" is from mid-15c. Reflexive sense of "control oneself, put restraint upon oneself" is from late 14c. Related: Refrained; refraining.

1560s, "fix securely (a driven nail) by bending and beating it back," a variant of clench (q.v.). The sense of "settle decisively" is first recorded 1716, from the notion of "clinching" the point of a nail to keep it fast. Boxing sense is from 1860. Related: Clinched; clinching.

1610s, also ettuy, etwee from French étui, Old French estui (12c.) "case, box, container," back-formation from estuier "put in put aside, spare; to keep, shut up, imprison," which is of uncertain origin. Perhaps from Latin studere "to be diligent."

mid-15c., detencioun, "act of keeping back or withholding," from Old French détention (13c.) and directly from Late Latin detentionem (nominative detentio), noun of action from past-participle stem of Latin detinere "hold back, keep off" (see detain).

Sense of "confinement, restraint, state of being detained" is by 1570s (in reference to Mary Queen of Scots). In reference to "a keeping in" as a school punishment, from 1857.