Etymology
Advertisement
re-enter (v.)

mid-15c., reentren, "to enter (a place) again or anew," from re-, denoting "repetition of an action," + enter. By 1838 in reference to an account or record. Related: Re-entered; re-entering.

Related entries & more 
Advertisement
enter (v.)

late 13c. entren, "enter into a place or a situation; join a group or society" (trans.); early 14c., "make one's entrance" (intrans.), from Old French entrer "enter, go in; enter upon, assume; initiate," from Latin intrare "to go into, enter" (source of Spanish entrar, Italian entrare), from intra "within," related to inter (prep., adv.) "among, between," from PIE *enter "between, among," comparative of root *en "in."

Transitive and intransitive in Latin; in French intransitive only. From c. 1300 in English as "join or engage in: (an activity);" late 14c. as "penetrate," also "have sexual intercourse" (with a woman);" also "make an entry in a record or list," also "assume the duties" (of office, etc.). Related: Entered; entering.

Related entries & more 
-re 

word-ending that sometimes distinguish British from American English. In the U.S., the change from -re to -er (to match pronunciation) in words such as fibre, centre, theatre began in late 18c. and became standard there over the next 25 years at the urging of Noah Webster (the 1804 edition of his speller, and especially his 1806 dictionary). The -re spelling, like -our, however, had the authority of Johnson's dictionary behind it and was unmoved in Britain, where it came to be a point of national pride, contra the Yankees.

Despite Webster's efforts, -re was retained in words with -c- or -g- (such as ogre, acre, the latter of which Webster insisted to the end of his days ought to be aker, and it was so printed in editions of the dictionary during his lifetime). The -re spelling generally is more justified by conservative etymology, based on French antecedents. It is met today in the U.S. only in Theatre as an element in the proper names of entertainment showplaces, where it is perhaps felt to inspire a perception of bon ton.

Related entries & more 
re 

"with reference to," used from c. 1700 in legalese, from Latin (in) re "in the matter of," from ablative of res "property, goods; matter, thing, affair," from Proto-Italic *re-, from PIE *reh-i- "wealth, goods" (source also of Sanskrit rayi- "property, goods," Avestan raii-i- "wealth"). Its non-legalese use is execrated by Fowler in three different sections of "Modern English Usage."

Related entries & more 
*re- 

*rē-, Proto-Indo-European root meaning "to reason, count;" a variant of PIE root *ar-, also arə-, "to fit together." 

It forms all or part of: Alfred; arraign; arithmetic; Conrad; dread; Eldred; Ethelred; hatred; hundred; kindred; logarithm; Ralph; rate (n.) "estimated value or worth;" rathskeller; ratify; ratio; ration; read; reason; rede; rhyme; riddle (n.1) "word-game;" rite; ritual.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit radh- "to succeed, accomplish;" Greek arithmos "number, amount;" Latin reri "to consider, confirm, ratify," ritus "rite, religious custom;" Old Church Slavonic raditi "to take thought, attend to;" Old Irish im-radim "to deliberate, consider;" Old English rædan "to advise, counsel, persuade; read;" Old English, Old High German rim "number;" Old Irish rim "number," dorimu "I count."

Related entries & more 
Advertisement
re- 

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]
Related entries & more 
re-evaluate (v.)

also reevaluate, "evaluate again," 1903, from re- + evaluate. Related: Re-evaluated; re-evaluating.

Related entries & more 
re-lay (v.)

"to lay again, lay a second time" 1580s, from re- "back, again" + lay (v.). With hyphenated spelling and full pronunciation of the prefix to distinguish it from relay. Related: Re-laid; re-laying.

Related entries & more 
re-enforcement (n.)

also reenforcement, "act of re-enforcing; state of being re-enforced; that which gives fresh strength to," c. 1600, from re- "back, again" + enforcement or else formed as a noun to go with re-enforce. Compare reinforcement.

Related entries & more 
re-charge (v.)

"rush at or attack back or again," intransitive, 1590s, from re- "back, again" + charge (v.). Related: Re-charged; re-charging.

Related entries & more