The Collaborative International Dictionary of English v.0.48:

Lour \Lour\, n. [Native name.] (Zool.)
   An Asiatic sardine (Clupea Neohowii), valued for its oil.
   [1913 Webster]

WordNet (r) 3.0 (2006):

lour
    v 1: set lower; "lower a rating"; "lower expectations" [syn:
         lower, lour]
    2: make lower or quieter; "turn down the volume of a radio"
       [syn: turn down, lower, lour]
    3: look angry or sullen, wrinkle one's forehead, as if to signal
       disapproval [syn: frown, glower, lour, lower]

Moby Thesaurus II by Grady Ward, 1.0:

286 Moby Thesaurus words for "lour":
   abase, abash, abated, ablated, abridge, apprehend, approach,
   attenuated, await, bated, be imminent, be in store, bear down,
   beat down, belittled, bludgeon, bode, bore, break, brew,
   bring down, bring low, bulldoze, bump, burrow, bust, cast down,
   cave, cave in, cheapen, color, come on, comminate, common,
   compress, confront, consumed, contracted, couch, countersink,
   croak, crush, curtail, curtailed, cut, cut back, cut down,
   cut prices, damp, dampen, dampen the spirits, darken, darkle, dash,
   debase, decline, decrease, decreased, deduct, deepen, deflate,
   deflated, degrade, deject, delve, demean, demeaning, demote,
   denounce, deplume, depreciate, depress, detrude, devaluate, dig,
   dig out, dike, dim, diminish, diminished, disadvantaged,
   discourage, disgrade, dishearten, dispirit, displume, dissipated,
   dive, down, downbear, downgrade, draw near, draw nigh, draw on,
   dredge, drill, drive, droop, dropped, dump, dump on, dusk, earlier,
   eroded, excavate, face, fall, fall in price, fallen, flop,
   flop down, flump, flump down, flush, forebode, forewarn, forthcome,
   founder, frown, furrow, gather, give way, glare, gloam, gloom,
   gloominess, glower, gnarl, go down, gouge, gouge out, grimace,
   groove, grow dark, grow dim, growl, grub, hang over, haul down,
   have a premonition, have a presentiment, hover, humble, impend,
   in the shade, indent, inferior, infra dig, intimidate, jew down,
   junior, knit the brow, knock down, lapse, less, lessen, lesser,
   let down, lie over, long face, look black, look daggers,
   look sullen, look threatening, loom, low, lower, lower the spirits,
   lowered, lowering, lowest, lowly, make a lip, make a moue, mantle,
   mark down, menace, mine, miniaturized, minor, modest, mope, moue,
   mow, near, nether, nose-dive, oppress, ordinary, overhang, pare,
   plop, plop down, plummet, plump, plunge, portend, pout,
   preapprehend, press down, pull down, push down, put down, quarry,
   redden, reduce, reduced, retrench, retrenched, roll back, sadden,
   sag, sap, scale down, scaled-down, scoop, scoop out, scowl,
   scrabble, scrape, scratch, second rank, second string, secondary,
   servile, set, set down, settle, settle down, shave, shorn, shorten,
   shorter, shovel, shrunk, shrunken, simplify, sink, sink down,
   slash, slouch, slump, slump down, smaller, snap, snarl, somber,
   somberness, sombrousness, spade, spit, step down, strip of rank,
   sub, subaltern, subjacent, subject, submerge, subordinate,
   subservient, subside, sulk, swag, take down, take from, third rank,
   third string, threaten, thrust down, trench, trim, trip up, trough,
   tune down, tunnel, under, underprivileged, utter threats against,
   vulgar, warn, watered-down, weakened, weigh heavy upon, weigh upon,
   worn, wry face