[1] : The Collaborative International Dictionary of English v.0.48

underscore \un`derscore"\, v. t.
   to draw a mark or line under; to underline. --j. tucker.
   1913 webster

[2] : WordNet (r) 2.0

underscore
     n : a line drawn underneath especially under written matter
         syn: underline
     v 1: give extra weight to a communication; "her gesture
          emphasized her words" syn: underline, emphasize, emphasise
     2: draw a line or lines underneath to call attention to syn: underline
see also:
underline emphasize emphasise 

[3] : Moby Thesaurus II by Grady Ward, 1.0

103 moby thesaurus words for "underscore":
   accent, accentuate, band, bar, belabor, blaze, blaze a trail,
   blemish, blotch, brand, chalk, chalk up, check, check off,
   cicatrize, cross-hatching, dapple, dash, define, delimit,
   delineation, demarcate, diagonal, discolor, dot, dotted line,
   dwell on, emphasize, engrave, feature, fleck, freckle, gash,
   give emphasis to, hachure, hairline, harp on, hatch, hatching,
   highlight, impress, imprint, italicize, line, lineation,
   make a mark, mark, mark off, mark out, mottle, nick, notch,
   overaccentuate, overemphasize, overstress, pencil, pepper,
   place emphasis on, play up, point, point up, prick, print, punch,
   punctuate, puncture, riddle, rub in, scar, scarify, score, scotch,
   scratch, seal, seam, slash, speck, speckle, splotch, spot,
   spotlight, stain, stamp, star, stigmatize, streak, streaking,
   stress, striate, striation, strip, stripe, striping, stroke,
   sublineation, tattoo, tick, tick off, trace, underline,
   underlining, underscoring, virgule

[4] : The Free On-line Dictionary of Computing (27 SEP 03)

underscore
     
         _, ascii 95.
     
        common names: itu-t: underline; underscore; underbar; under.
        rare: score; backarrow; skid; intercal: flatworm.
     
        see also left arrow.
     
        1995-03-06
     
     
see also:
ascii itu-t intercal left arrow 

Underscore >> U Words
Underscore, definition of term: Underscore
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