request (n.)

mid-14c., requeste, "act of asking for a favor, service, etc.; expression of desire for something to be granted or done," from Old French requeste (Modern French requête) "a request," from Vulgar Latin *requaesita, from Latin requisita (res) "(a thing) asked for," from fem. of requisitus "requested, demanded," past participle of requirere "seek to know, ask, ask for" (see require).

From late 14c. as "that which one asks for." By 1928 as "a letter, telephone call, etc., asking for a particular song to be played on a radio program, often accompanied by a personal message or dedication."

Related entries & more 
request (v.)

1530s, "ask (someone) to (do something), express desire for something to be done;" 1560s, "express a wish or desire, ask to be allowed to do something," from request (n.) or from French requester, "ask again, request, reclaim," from requeste. The older verb was Middle English requeren (14c.), from Old French requerre and directly from Latin requiare. Related: Requested; requesting.

Related entries & more 
require (v.)

late 14c., requeren, "to ask (someone) a question, inquire," a sense now obsolete, from Old French requerre, requerir "seek, procure; beg, ask, petition; demand," from Vulgar Latin *requaerere, from Latin requirere "seek to know, ask, ask for (something needed)," from re-, here perhaps meaning "repeatedly" (see re-), + quaerere "ask, seek" (see query (v.)). In some later English senses probably directly from Latin.

Still in 16c.-17c. commonly "to ask or request (to have or do something)," but this original sense of the word has been taken over by request (v.).

Also from late 14c. as "to stand in need of, want; to need for some end or purpose." The sense of "demand that (someone) do (something)" is from 1751, via the notion of "to ask for imperatively, or as a right" (late 14c.). The meaning "demand as necessary or essential on general principles" is from early 15c. Related: Required; requiring.

Related entries & more 

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 
prex (n.)
U.S. college slang for president (of a college), 1828. As a Latin verb, it meant "a request, entreaty."
Related entries & more 
petition (v.)

"make a request to," c. 1600, from petition (n.) or from or inspired by French pétittioner, from the noun in French. Related: Petitioned; petitioning.

Related entries & more 
postulate (n.)

1580s, "a request, demand, petition," from Latin postulātum "demand, request," properly "that which is requested," noun use of neuter past participle of postulare "to ask, demand; claim; require" (see postulate (v.)).

The sense in logic, "proposition proposed for acceptance without proof, something taken for granted," is from 1640s, from a sense in Medieval Latin. The meaning "self-evident practical proposition" is by 1751. The earlier noun in English was postulation "a petition, request" (c. 1400). Middle English also had postulate (adj.) "nominated to a bishopric or archbishopric" (mid-15c.).

Related entries & more 
petition (n.)

mid-14c., petiocioun, "a supplication or prayer," especially to a deity," from Anglo-French (early 14c.), from Old French peticion "request, petition" (12c., Modern French pétition) and directly from Latin petitionem (nominative petitio) "a blow, thrust, attack, aim; a seeking, searching," in law "a claim, suit," noun of action from past-participle stem of petere "to make for, go to; attack, assail; seek, strive after; ask for, beg, beseech, request; fetch; derive; demand, require," from PIE root *pet- "to rush; to fly."

Meaning "formal written request to a superior (earthly)" is attested from early 15c. In law, "a written application for an order of the court" (1737).

Related entries & more 
entreaty (n.)
mid-15c., "treatment; negotiation;" see entreat + -y (1). Meaning "urgent solicitation, earnest request" is from 1570s. Related: Entreaties.
Related entries & more 
unsolicited (adj.)
1580s, "unpetitioned, not approached with a request," from un- (1) "not" + past participle of solicit (v.). Meaning "not asked for, unsought" is from 1680s.
Related entries & more