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Synonyms for Bum (same or very similar meaning)

WordNet sense 1 (a disreputable vagrant):
hobo, tramp

WordNet sense 2 (a person who is deemed to be despicable or contemptible):
crumb, lowlife, puke, rat, skunk, so-and-so, stinker, git, rotter, stinkpot, dirty dog

WordNet sense 3 (person who does no work):
do-nothing, idler, loafer, layabout

WordNet sense 4 (the fleshy part of the human body that you sit on):
backside, behind, bottom, buns, buttocks, can, derriere, fanny, hindquarters, posterior, rear, rump, seat, stern, tail, tush, arse, fundament, keister, nates, prat, tooshie, tush, tail end, hind end

WordNet sense 5 (be lazy or idle):
loaf, loll, arse around, arse about, bum about, bum around, frig around, loll around, lounge about, lounge around, waste one's time, fuck off

WordNet sense 6 (of very poor quality; flimsy):
cheap, cheesy, chintzy, crummy, punk, sleazy, tinny

WordNet sense 7 (of low or inferior quality):

WordNet sense 8 (ask for and get free; be a parasite):
cadge, grub, mooch, sponge

From the ODE community, based on WordNetadd/edit