repatriation n.

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]

1590s, "compatriot," from French patriote (15c.) and directly from Late Latin patriota "fellow-countryman" (6c.), from Greek patriotes "fellow countryman," from patrios "of one's fathers," patris "fatherland," from pater (genitive patros) "father" (see father (n.)); with -otes, suffix expressing state or condition. Liddell & Scott write that patriotes was "applied to barbarians who had only a common [patris], [politai] being used of Greeks who had a common [polis] (or free-state)."

Meaning "loyal and disinterested lover and defender of one's country and its interests" is attested from c. 1600, but it became an ironic term of ridicule or abuse from mid-18c. in England, so that Johnson, who at first defined it as "one whose ruling passion is the love of his country," in his fourth edition added, "It is sometimes used for a factious disturber of the government."

The name of patriot had become [c. 1744] a by-word of derision. Horace Walpole scarcely exaggerated when he said that ... the most popular declaration which a candidate could make on the hustings was that he had never been and never would be a patriot. [Macaulay, "Horace Walpole," 1833]

It was somewhat revived in reference to resistance movements in overrun countries in World War II, and it has usually had a positive sense in American English, where the phony and rascally variety has been consigned to the word patrioteer (1928).

Oriana Fallaci ["The Rage and the Pride," 2002] marvels that Americans, so fond of patriotic, patriot, and patriotism, lack the root noun and are content to express the idea of patria by cumbersome compounds such as homeland. (Joyce, Shaw, and H.G. Wells all used patria as an English word early 20c., but it failed to stick.) Patriots' Day (April 19, the anniversary of the 1775 skirmishes at Lexington and Concord Bridge) was observed as a legal holiday in Maine and Massachusetts from 1894.