"bring together or into order again by urgent effort," c. 1600, from French rallier, from Old French ralier "reassemble, unite again," from re- "again" (see re-) + alier "unite" (see ally (v.)).

In Old French (and Italian), re- often appeared as ra- by confusion with the true ra- (from Latin re- + ad-), and the following consonant often was doubled; compare rabbet (a doublet of rebate), rappel (a doublet of repeal). But as ra- was not recognized in English as a prefix, words with ra- in Old French usually returned to re- in English; Rally and rabbet never were because the accent had receded. In later borrowings (rappel, rapprochement, etc.) the words tend to keep their French forms. 

Intransitive meaning "pull together hastily, recover order, revive, rouse" is from 1660s. Related: Rallied; rallying. Rallying-point "place at or about which persons come together for action" is by 1798. Rally round the flag (1862) is a line from popular American Civil War song "Battle Cry of Freedom."

"earthen elevation around a place for fortification," capable of resisting cannon shot and sometimes also including parapets, 1580s, from French rempart, rampart, from remparer "to fortify," from re- "again" (see re-) + emparer "fortify, take possession of," from Old Provençal amparer, from Vulgar Latin *anteparare "prepare," properly "to make preparations beforehand," from Latin ante "before" (from PIE root *ant- "front, forehead," with derivatives meaning "in front of, before") + parare "to get, prepare" (from PIE root *pere- (1) "to produce, procure"). With unetymological -t in French, perhaps by influence of boulevart (see boulevard).

13c., raunsoun, "sum paid for the release of a prisoner or captured man," also "redemption from damnation," from Old French ranson (Modern French rançon), earlier raenson "ransom, redemption," from Latin redemptionem (nominative redemptio) "a redeeming," from redimere "to redeem, buy back," from red- "back" (see re-) + emere "to take, buy, gain, procure" (from PIE root *em- "to take, distribute"). A doublet of redemption. A faded word somewhat revived by Scott early 19c. Spelling with -m appears by late 14c., but the reason for it is unclear (compare seldom, random).

c. 1300, "resisting an established or rightful government or law, insurrectionist; lawless," from Old French rebelle "stubborn, obstinate, rebellious" (12c.) and directly from Latin rebellis "insurgent, rebellious," from rebellare "to rebel, revolt," from re- "opposite, against," or perhaps "again" (see re-) + bellare "wage war," from bellum "war" (see bellicose). By 1680s as "belonging to or controlled by rebels."

"build up again, construct what has been demolished," c. 1600 (implied in rebuilding), from re- "back, again" + build (v.). Related: Rebuilt.

c. 1300, receiven, "take into one's possession, accept possession of," also in reference to the sacrament, from Old North French receivre (Old French recoivre) "seize, take hold of, pick up; welcome, accept," from Latin recipere "regain, take back, bring back, carry back, recover; take to oneself, take in, admit," from re- "back," though the exact sense here is obscure (see re-) + -cipere, combining form of capere "to take" (from PIE root *kap- "to grasp").

From c. 1300 as "welcome (in a specified manner)." From early 14c. as "catch in the manner of a receptacle." From mid-14c. as "obtain as one's reward." From late 14c. as "accept as authoritative or true;" also late 14c. as "have a blow or wound inflicted." Radio and (later) television sense is attested from 1908. Related: Received; receiving. Receiving line is by 1933.

Other obsolete English verbs from the same Latin word in different forms included recept "to receive, take in" (early 15c., recepten, from Old French recepter, variant of receter and Latin receptus). Also compare receipt, which also had a verb form in Middle English, receiten.

late 14c., recommenden, "praise, present as worthy; commit (to another) for care or protection," from Medieval Latin recommendare, from Latin re-, here perhaps an intensive prefix, or else from a sense now obscure (see re-), + commendare "commit to one's care, commend" (see commend). Meaning "advise as to action, urge" (that something be done) is from 1746. Related: Recommended; recommending.

c. 1300, recoveren, "to regain consciousness," also "regain health or strength after sickness, injury, etc.," from Anglo-French rekeverer (13c.), Old French recovrer "come back, return; regain health; procure, get again" (11c.), from Medieval Latin recuperare "to recover" (source of Spanish recobrar, Italian ricoverare; see recuperation).

The sense of "get (anything) back, get or regain possession or control of," literally or figuratively, after it has been lost, is attested from mid-14c. In law, "obtain by judgment or legal proceedings," late 14c. The transitive sense of "restore from sickness, restore (another) to health" is from c. 1600; that of "rescue, save from danger" is from 1610s. Related: Recovered; recovering. To recover arms (1680s) is to bring the piece from the position of "aim" to that of "ready."

mid-14c., "a return to health after illness, injury, misfortune, etc.," from Anglo-French recoverie (c. 1300), Old French recovree "remedy, cure, recovery," from past-participle stem of recovrer (see recover).

The meaning "a gaining possession (of property) by legal action" is from early 15c. The general (non-legal) sense of "act or power of regaining or retaking" (something lost or taken away) is by 1530s. That of "act of righting oneself after a blunder, mishap, etc." is from 1520s. The meaning "restoration from a bad to a good condition" is from 1580s.

also re-create, "to create anew, make again," 1580s, from re- "back, again," here, "repetition of an action," + create. Related: Recreated; recreating.