early 15c., "inclined to fighting," from Latin bellicosus "warlike, valorous, given to fighting," from bellicus "of war," from bellum "war" (Old Latin duellum, dvellum), which is of uncertain origin.

The best etymology for duellum so far has been proposed by Pinault 1987, who posits a dim. *duelno- to bonus. If *duelno- meant 'quite good, quite brave', its use in the context of war ( bella acta, bella gesta) could be understood as a euphemism, ultimately yielding a meaning 'action of valour, war' for the noun bellum. [de Vaan]

abbreviation of rebel (n.), 1862, a word from the U.S. Civil War, in which the Confederates embraced the North's designation of them as rebels. Along with rebelism (1862), rebeldom "the region or sphere of rebels" (1862) and others, for which see rebel (n.).

"war waged against a government by some portion of its subjects" (originally especially against God or Church authority), mid-14c., rebellioun, from Old French rebellion (14c.) and directly from Latin rebellionem (nominative rebellio) "rebellion, revolt; renewal of war," from rebellis "insurgent, rebellious" (see rebel (adj.)).

"insubordinate, defying lawful authority, acting as rebels do or having the disposition of one," early 15c., from Latin rebellis (see rebel (adj.)) + -ous. Of things, "hard to treat or deal with," 1570s. Another old word for it was rebellant (early 15c.). Related: Rebelliously; rebelliousness.

late 14c. (c. 1200 as a surname), "riotous merry-making," also an occasion of this, from Old French revel, resvel "entertainment, revelry," verbal noun from reveler, also rebeller (14c.) "be disorderly, make merry" (see rebel (adj.)). "The development of sense in OF. is 'rebellion, tumult, disturbance, noisy mirth'" [OED].

Formerly especially a kind of dance or performance given in connection with masks or pageants, a dancing procession (usually revels). Related: revel-rout "riotous throng."

word-forming element meaning "back, back from, back to the original place;" also "again, anew, once more," also conveying the notion of "undoing" or "backward," etc. (see sense evolution below), c. 1200, from Old French re- and directly from Latin re- an inseparable prefix meaning "again; back; anew, against."

Watkins (2000) describes this as a "Latin combining form conceivably from Indo-European *wret-, metathetical variant of *wert- "to turn." De Vaan says the "only acceptable etymology" for it is a 2004 explanation which reconstructs a root in PIE *ure "back."

In earliest Latin the prefix became red- before vowels and h-, a form preserved in redact, redeem, redolent, redundant, redintegrate, and, in disguise, render (v.). In some English words from French and Italian re- appears as ra- and the following consonant is often doubled (see rally (v.1)).

The many meanings in the notion of "back" give re- its broad sense-range: "a turning back; opposition; restoration to a former state; "transition to an opposite state." From the extended senses in "again," re- becomes "repetition of an action," and in this sense it is extremely common as a formative element in English, applicable to any verb. OED writes that it is "impossible to attempt a complete record of all the forms resulting from its use," and adds that "The number of these is practically infinite ...."  

Often merely intensive, and in many of the older borrowings from French and Latin the precise sense of re- is forgotten, lost in secondary senses, or weakened beyond recognition, so that it has no apparent semantic content (receive, recommend, recover, reduce, recreate, refer, religion, remain, request, require).

There seem to have been more such words in Middle English than after, e.g. recomfort (v.) "to comfort, console; encourage;" recourse (n.) "a process, way, course." Recover in Middle English also could mean "obtain, win" (happiness, a kingdom, etc.) with no notion of getting something back, also "gain the upper hand, overcome; arrive at;" also consider the legal sense of recovery as "obtain (property) by judgment or legal proceedings." 

And, due to sound changes and accent shifts, re- sometimes entirely loses its identity as a prefix (rebel, relic, remnant, restive, rest (n.2) "remainder," rally (v.1) "bring together"). In a few words it is reduced to r-, as in ransom (a doublet of redemption), rampart, etc.

It was used from Middle English in forming words from Germanic as well as Latin elements (rebuild, refill, reset, rewrite), and was used so even in Old French (regret, regard, reward, etc.).

Prefixed to a word beginning with e, re- is separated by a hyphen, as re-establish, re-estate, re-edify, etc. ; or else the second e has a dieresis over it: as, reëstablish, reëmbark, etc. The hyphen is also sometimes used to bring out emphatically the sense of repetition or iteration : as, sung and re-sung. The dieresis is not used over other vowels than e when re is prefixed : thus, reinforce, reunite, reabolish. [Century Dictionary, 1895]