The Collaborative International Dictionary of English v.0.48:

Leer \Leer\, a. [OE. lere; akin to G. leer, OHG. & OS. l[=a]ri.]
   [Obs. or Prov. Eng.]
   Empty; destitute; wanting; as:
   (a) Empty of contents. "A leer stomach." --Gifford.
   (b) Destitute of a rider; and hence, led, not ridden; as, a
       leer horse. --B. Jonson.
   (c) Wanting sense or seriousness; trifling; trivolous; as,
       leer words.
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The Collaborative International Dictionary of English v.0.48:

Leer \Leer\, n.
   An oven in which glassware is annealed.
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The Collaborative International Dictionary of English v.0.48:

Leer \Leer\, n. [OE. lere cheek, face, look, AS. hle['o]r cheek,
   face; akin to OS. hlear, hlior, OD. lier, Icel. hl[=y]r.]
   1. The cheek. [Obs.] --Holinshed.
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   2. Complexion; aspect; appearance. [Obs.]
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            A Rosalind of a better leer than you. --Shak.
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   3. A distorted expression of the face, or an indirect glance
      of the eye, conveying a sinister or immodest suggestion.
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            With jealous leer malign
            Eyed them askance.                    --Milton.
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            She gives the leer of invitation.     --Shak.
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            Damn with faint praise, assent with civil leer.
                                                  --Pope.
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The Collaborative International Dictionary of English v.0.48:

Leer \Leer\ (l[=e]r), v. t.
   To learn. [Obs.] See Lere, to learn.
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The Collaborative International Dictionary of English v.0.48:

Leer \Leer\, v. i. [imp. & p. p. Leered (l[=e]rd); p. pr. &
   vb. n. Leering.]
   To look with a leer; to look askance with a suggestive
   expression, as of hatred, contempt, lust, etc.; to cast a
   sidelong lustful or malign look.
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         I will leerupon him as a' comes by.      --Shak.
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         The priest, above his book,
         Leering at his neighbor's wife.          --Tennyson.
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The Collaborative International Dictionary of English v.0.48:

Leer \Leer\, v. t.
   To entice with a leer, or leers; as, to leer a man to ruin.
   --Dryden.
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WordNet (r) 3.0 (2006):

leer
    n 1: a facial expression of contempt or scorn; the upper lip
         curls [syn: sneer, leer]
    2: a suggestive or sneering look or grin
    v 1: look suggestively or obliquely; look or gaze with a sly,
         immodest, or malign expression; "The men leered at the
         young women on the beach"

Moby Thesaurus II by Grady Ward, 1.0:

139 Moby Thesaurus words for "leer":
   Roman candle, aid to navigation, alarm, amber light, balefire,
   beacon, beacon fire, beat the drum, bell, bell buoy, blinker,
   blue peter, buoy, caution light, contemplate, dekko, dip, examine,
   exchange colors, eye, eyeful, flag, flag down, flare, flash, fleer,
   fog bell, fog signal, fog whistle, foghorn, give a signal,
   give the eye, give the nod, give the once-over, glad eye, glance,
   go light, gong buoy, green light, hail, hail and speak, half-mast,
   hard look, heliograph, high sign, hoist a banner, inspect,
   international alphabet flag, international numeral pennant, kick,
   leer at, leering look, look, look over, look-in, lustful leer,
   make a sign, marker beacon, nod, nudge, ogle, ogle at,
   parachute flare, peruse, pilot flag, poke, police whistle, pore,
   pore over, preview, prospect, quarantine flag, radio beacon,
   raise a cry, red flag, red light, regard, rocket, sailing aid,
   salute, sardonic grin, scene, scornful laugh, scrutinize,
   semaphore, semaphore flag, semaphore telegraph, sidelong look,
   sight, sign, signal, signal beacon, signal bell, signal fire,
   signal flag, signal gong, signal gun, signal lamp, signal light,
   signal mast, signal post, signal rocket, signal shot, signal siren,
   signal tower, signalize, size up, sly look, smirk, sneer, snicker,
   snigger, snort, sound an alarm, sound the trumpet, spar buoy,
   speak, stop light, survey, take a long, take stock of, the eye,
   the nod, the wink, touch, traffic light, traffic signal,
   unfurl a flag, vet, view, watch fire, wave, wave a flag,
   wave the hand, white flag, wigwag, wigwag flag, wink,
   yellow flag