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

bum \bum\ bu^m, n. contr. fr. bottom in this sense.
   the buttock. low --shak.
   1913 webster

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

bum \bum\, v. i. imp.  p. p. bummed; p. pr.  vb. n.
   bumming ?. see boom, v. i., to roar.
   to make murmuring or humming sound. --jamieson.
   1913 webster

   to bum around to wander about idly or aimlessly.
      pjc
see also:
bummed bumming boom to bum around 

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

bum \bum\ bu^m, v. t.
   to borrow without intention of returning; to cadge; as, to
   bum a cigarette; to bum a cup of coffee; -- usually with
   inexpensive items as the object. informal
   pjc

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

bum \bum\, n.
   a humming noise. --halliwell.
   1913 webster

[5] : WordNet (r) 2.0

bum
     adj : of very poor quality syn: cheap, cheesy, chintzy, crummy,
            punk, sleazy, tinny
     n 1: a person who is deemed to be despicable or contemptible;
          "only a rotter would do that"; "kill the rat"; "throw
          the bum out"; "you cowardly little pukes"; "the british
          call a contemptible person a `git'" syn: rotter, dirty
          dog, rat, skunk, stinker, stinkpot, puke, crumb,
           lowlife, scum bag, so-and-so, git
     2: a disreputable vagrant; "a homeless tramp"; "he tried to
        help the really down-and-out bums" syn: tramp, hobo
     3: person who does no work; "a lazy bum" syn: idler, loafer,
         do-nothing, layabout
     4: the fleshy part of the human body that you sit on; "he
        deserves a good kick in the butt"; "are you going to sit
        on your fanny and do nothing?" syn: buttocks, nates,
        arse, butt, backside, buns, can, fundament, hindquarters,
         hind end, keister, posterior, prat, rear, rear
        end, rump, stern, seat, tail, tail end, tooshie,
         tush, bottom, behind, derriere, fanny, ass
     v 1: ask for and get free; be a parasite syn: mooch, cadge,
          grub, sponge
     2: be lazy or idle; "her son is just bumming around all day"
        syn: bum around, bum about, arse around, arse
        about, fuck off, loaf, frig around, waste one's
        time, lounge around, loll, loll around, lounge
        about
     also: bumming, bummed
see also:
cheap cheesy chintzy crummy punk sleazy 
tinny rotter dirty dog rat skunk 
stinker stinkpot puke crumb lowlife 
scum bag so-and-so git tramp hobo 
idler loafer do-nothing layabout buttocks 
nates arse butt backside buns 
can fundament hindquarters hind end keister 
posterior prat rear rear end rump 
stern seat tail tail end tooshie 
tush bottom behind derriere fanny 
ass mooch cadge grub sponge 
bum around bum about arse around arse about fuck off 
loaf frig around waste one's time lounge around loll 
loll around lounge about bumming bummed 

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

223 moby thesaurus words for "bum":
   arab, bowery bum, amiss, arse, ass, backside, bad, barfy,
   bat around, beach bum, beachcomber, beg, beggar, beggarly fellow,
   bender, birr, blighter, bo, bombilate, bombinate, boom, booze,
   boozehound, bottle sucker, bottom, brannigan, budmash, bumble,
   bummer, burr, bust, butt, buzz, cadge, cadger, caitiff, can,
   carouse, cheeks, cheesy, count ties, crappy, creepy, crummy,
   derelict, derriere, devil, dirty, dissatisfactory, divagate,
   do-nothing, dogie, dolittle, drift, drifter, drone, drunk,
   drunkard, elbow bender, faineant, fanny, flit, floater, gad,
   gad about, gallivant, gamin, gamine, ginhound, go about,
   go the rounds, godawful, goldbrick, good-for-naught,
   good-for-nothing, goof off, goshawful, grim, guttersnipe, hairy,
   hind end, hit, hit the road, hit the trail, hit up, hobo,
   homeless waif, hooch hound, hum, human wreck, icky, idler, jag,
   jaunt, keister, knock about, knock around, landloper, laze, lazy,
   lazybones, lazzarone, loaf, loafer, loiter, loll, losel, lounge,
   lowlife, lush, lusher, mauvais sujet, mean wretch, meander,
   mendicant, mendicant friar, mendicant order, mooch, moocher,
   mucker, mudlark, no-good, nomadize, panhandle, panhandler,
   pass the hat, pauvre diable, peregrinate, pererrate, piker,
   pilgarlic, poor, poor creature, poor devil, posterior, prat, prowl,
   punk, purr, putrid, ragamuffin, ragman, ragpicker, ramble, range,
   roam, rotten, rounder, rove, rum hound, rummy, rump, run about,
   rusty-dusty, sad case, sad sack, saunter, schnorrer, scrounge,
   scrounger, shitty, ski bum, skid-row bum, slouch, slug, slugabed,
   soak, souse, sponge, stern, stew, stiff, stinking, stinky,
   straggle, stray, street arab, street arab, street urchin, stroll,
   strum, sundowner, surf bum, swagman, swagsman, swillbelly,
   swillbowl, swillpot, tail, tatterdemalion, tennis bum, thrum,
   touch, traipse, tramp, truant, tuchis, turnpiker, tush, tushy,
   unsatisfactory, up, urchin, vag, vagabond, vagabondize, vagrant,
   vaurien, vomity, waif, waifs and strays, walk the tracks, wander,
   wassail, wastrel, wayfare, whir, whiz, wino, worthless fellow,
   wretch, wrong, yecchy

[7] : Jargon File (4.3.1, 29 Jun 2001)

bum 1. vt. to make highly efficient, either in time or space, often at
   the expense of clarity. "i managed to bum three more instructions out of
   that code." "i spent half the night bumming the interrupt code." in
   1996, this term and the practice it describes are semi-obsolete. in
   elder days, john mccarthy inventor of lisp used to compare some
   efficiency-obsessed hackers among his students to "ski bums"; thus,
   optimization became "program bumming", and eventually just "bumming". 2.
   to squeeze out excess; to remove something in order to improve whatever
   it was removed from without changing function; this distinguishes the
   process from a featurectomy. 3. n. a small change to an algorithm,
   program, or hardware device to make it more efficient. "this hardware
   bum makes the jump instruction faster." usage: now uncommon, largely
   superseded by v. tune and n. tweak, hack, though none of these
   exactly capture sense 2. all these uses are rare in commonwealth
   hackish, because in the parent dialects of english the noun `bum' is a
   rude synonym for `buttocks' and the verb `bum' for buggery.


see also:
elder days lisp featurectomy tune tweak hack 

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

bum
     
        1. to make highly efficient, either in time or space, often at
        the expense of clarity.  "i managed to bum three more
        instructions out of that code."  "i spent half the night
        bumming the interrupt code."  in elder days, john mccarthy
        inventor of lisp used to compare some efficiency-obsessed
        hackers among his students to "ski bums"; thus, optimisation
        became "program bumming", and eventually just "bumming".
     
        2. to squeeze out excess; to remove something in order to
        improve whatever it was removed from without changing
        function; this distinguishes the process from a
        featurectomy.
     
        3.  a small change to an algorithm, program, or hardware
        device to make it more efficient.  "this hardware bum makes
        the jump instruction faster."
     
        usage: now uncommon, largely superseded by v. tune and
        tweak, hack, though none of these exactly capture sense
        2.  all these uses are rare in commonwealth hackish, because
        in the parent dialects of english "bum" is a rude synonym for
        "buttocks".
     
        jargon file
     
     
see also:
elder days john mccarthy lisp featurectomy tune tweak 
hack jargon file 

Bum >> B Words
Bum, definition of term: Bum
bum_pag1.html