respire v.

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]

mid-13c., "animating or vital principle in man and animals," from Anglo-French spirit, Old French espirit "spirit, soul" (12c., Modern French esprit) and directly from Latin spiritus "a breathing (respiration, and of the wind), breath; breath of a god," hence "inspiration; breath of life," hence "life;" also "disposition, character; high spirit, vigor, courage; pride, arrogance," related to spirare "to breathe," perhaps from PIE *(s)peis- "to blow" (source also of Old Church Slavonic pisto "to play on the flute"). But de Vaan says "Possibly an onomatopoeic formation imitating the sound of breathing. There are no direct cognates."

Meaning "supernatural immaterial creature; angel, demon; an apparition, invisible corporeal being of an airy nature" is attested from mid-14c.; from late 14c. as "a ghost" (see ghost (n.)). From c. 1500 as "a nature, character"; sense of "essential principle of something" (in a non-theological context, as in Spirit of St. Louis) is attested from 1680s, common after 1800; Spirit of '76 in reference to the qualities that sparked and sustained the American Revolution is attested by 1797 in William Cobbett's "Porcupine's Gazette and Daily Advertiser."

From late 14c. in alchemy as "volatile substance; distillate;" from c. 1500 as "substance capable of uniting the fixed and the volatile elements of the philosopher's stone." Hence spirits "volatile substance;" sense narrowed to "strong alcoholic liquor" by 1670s. This also is the sense in spirit level (1768). Also from mid-14c. as "character, disposition; way of thinking and feeling, state of mind; source of a human desire;" in Middle English freedom of spirit meant "freedom of choice." From late 14c. as "divine substance, divine mind, God;" also "Christ" or His divine nature; "the Holy Ghost; divine power;" also, "extension of divine power to man; inspiration, a charismatic state; charismatic power, especially of prophecy." Also "essential nature, essential quality." From 1580s in metaphoric sense "animation, vitality."

According to Barnhart and OED, originally in English mainly from passages in Vulgate, where the Latin word translates Greek pneuma and Hebrew ruah. Distinction between "soul" and "spirit" (as "seat of emotions") became current in Christian terminology (such as Greek psykhe vs. pneuma, Latin anima vs. spiritus) but "is without significance for earlier periods" [Buck]. Latin spiritus, usually in classical Latin "breath," replaces animus in the sense "spirit" in the imperial period and appears in Christian writings as the usual equivalent of Greek pneuma. Spirit-rapping is from 1852.

1836, "an aid to breathing," originally a sort of metallic gauze mask fitted to the face by a wire frame and meant to keep out smoke, dust, and especially cold air; agent noun from respire. The word was later used of gas masks in World War I. As "machine to provide artificial respiration" from 1929.