threadbare or faded from wear
a shabby sofa
dilapidated; run-down
a shabby district
dressed in worn or grubby clothes; seedy
a shabby tramp
shameful or despicable
What a shabby trick, driving off and leaving me to walk home!
shabbily adv
shabbiness noun
[from English dialect shab scab, a low fellow, from Old English sceabb]