Etymology
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leap (n.)
c. 1200, "the act or an act of leaping," from Old English hliep, hlyp (West Saxon), *hlep (Mercian, Northumbrian) "a leap, a bound, a spring; sudden movement; thing to leap from;" from Proto-Germanic *hlaupan (cognates: Old Frisian hlep, Dutch loop, Old High German hlouf, German lauf); from the root of leap (v.). Leaps has been paired with bounds at least since 1720.
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leap (v.)

c. 1200, from Old English hleapan "to jump, spring clear of the ground by force of an initial bound; run, go; dance, leap upon (a horse)" (class VII strong verb; past tense hleop, past participle hleapen), from Proto-Germanic *hlaupanan (source also of Old Saxon hlopan, Old Norse hlaupa, Old Frisian hlapa, Dutch lopen, Old High German hlouffan, German laufen "to run," Gothic us-hlaupan "to jump up"), of uncertain origin, with no known cognates beyond Germanic; perhaps a substratum word.

First loke and aftirward lepe [proverb recorded from mid-15c.]

Transitive sense "pass over by leaping" is from early 15c. Leap-frog, the children's game, is attested by that name from 1590s ("Henry V"); figurative use by 1704; as a verb from 1872. To leap tall buildings in a single bound (1940s) is from the description of Superman's powers. Related: Leaped; leaping.

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leap year (n.)
"year containing 366 days," late 14c., lepe gere (not in Old English), from leap (v.) + year. Probably so called from its causing fixed festival days, which normally advance one weekday per year, to "leap" ahead one day in the week. Compare Medieval Latin saltus lunae (Old English monan hlyp) "omission of one day in the lunar calendar every 19 years."

Dutch schrikkeljaar "leap year" is from Middle Dutch schricken "leap forward," literally "be startled, be in fear." The 29th of February is schrikkeldag. Danish skudaar, Swedish skottår are literally "shoot-year;" German schaltjahr is from schalten "insert, intercalate." The Late Latin phrase was annus bissextilis, source of the Romanic words; compare bissextile.
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interloper (n.)

1590s, enterloper, "unauthorized trader trespassing on privileges of chartered companies," probably a hybrid from inter- "between" + -loper (from landloper "vagabond, adventurer," also, according to Johnson, "a term of reproach used by seamen of those who pass their lives on shore"); perhaps from a dialectal form of leap, or from Middle Dutch loper "runner, rover," from lopen "to run," from Proto-Germanic *hlaupanan "to leap" (see leap (v.)).

OED says Dutch enterlooper "a coasting vessel; a smuggler" is later than the English word and said by Dutch sources to be from English. General sense of "self-interested intruder" is from 1630s.

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loop (n.)
late 14c., "a fold or doubling of cloth, rope, leather, cord, etc.," of uncertain origin. OED favors a Celtic origin (compare Gaelic lub "bend," Irish lubiam), which in English was perhaps influenced by or blended with Old Norse hlaup "a leap, run" (see leap (v.)). As a feature of a fingerprint, 1880. In reference to magnetic recording tape or film, first recorded 1931. Computer programming sense "sequence of instructions executed repeatedly" first attested 1947.
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lope (v.)
"to run with long strides," early 15c.; earlier "to leap, jump, spring" (c. 1300), from Old Norse hlaupa "to run, leap, spring up," from Proto-Germanic *hlaupan "to leap" (see leap (v.)). Related: Loped; loping. A lope-staff (c. 1600) was a pole used for leaping over marshes and dikes in low country.
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elope (v.)
1590s, "to run off," probably from Middle Dutch (ont)lopen "run away," from ont- "away from" (from Proto-Germanic *und- which also gave the first element in until, from PIE root *ant- "front, forehead," with derivatives meaning "in front of, before") + lopen "to run," from Proto-Germanic *hlaupan (source also of Old English hleapan; see leap (v.)). Sense of "run away in defiance of parental authority to marry secretly" is 19c.

In support of this OED compares Old English uðleapan, "the technical word for the 'escaping' of a thief." However there is an Anglo-French aloper "run away from a husband with one's lover" (mid-14c.) which complicates this etymology; perhaps it is a modification of the Middle Dutch word, with Old French es-, or it is a compound of that and Middle English lepen "run, leap" (see leap (v.)).

The oldest Germanic word for "wedding" is represented by Old English brydlop (source also of Old High German bruthlauft, Old Norse bruðhlaup), literally "bride run," the conducting of the woman to her new home. Related: Eloped; eloping.
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wallop (v.)
late 14c., "to gallop," possibly from Old North French *waloper (13c., Old French galoper), from Frankish compound *walalaupan "to run well" (compare Old High German wela "well," see well (adv.); and Old Low Franconian loupon "to run, leap," from Proto-Germanic *hlaupan; see leap (v.)). The meaning "to thrash" (1820) and the noun meaning "heavy blow" (1823) may be separate developments, of imitative origin. Related: Walloped; walloping.
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gantlet (n.)
"military punishment in which offender runs between rows of men who beat him in passing," 1640s, gantlope, gantelope, from Swedish gatlopp "passageway," from Old Swedish gata "lane" (see gate (n.)) + lopp "course," related to löpa "to run" (see leap (v.)). Probably borrowed by English soldiers during Thirty Years' War.

By normal evolution the Modern English form would be *gatelope, but the current spelling (first attested 1660s, not fixed until mid-19c.) is from influence of gauntlet (n.1) "a glove," "there being some vague association with 'throwing down the gauntlet' in challenge" [Century Dictionary].
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lapwing (n.)
Middle English lappewinke (late 14c.), lapwyngis (early 15c.), folk etymology alteration of Old English hleapewince "lapwing," probably literally "leaper-winker," from hleapan "to leap" (see leap (v.)) + wince "totter, waver, move rapidly," related to wincian "to wink" (see wink (v.)).

Said to be so called from "the manner of its flight" [OED] "in reference to its irregular flapping manner of flight" [Barnhart], but the lapwing also flaps on the ground pretending to have a broken wing to lure egg-hunters away from its nest, which seems a more logical explanation. Its Greek name was polyplagktos "luring on deceitfully."
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