Definition of bad
very intense; "a bad headache"; "in a big rage"; "had a big (or bad) shock"; "a bad earthquake"; "a bad storm"
not
capable of
being collected; "a bad (or uncollectible) debt"
nonstandard; "so-called bad grammar"
physically unsound or diseased; "has a bad back"; "a bad heart"; "bad teeth"; "an unsound limb"; "unsound teeth"
capable of harming; "bad air"; "smoking is bad for you"
reproduced fraudulently; "like a bad penny..."; "a forged
twenty dollar bill"
(noun)
that which is
below standard or expectations as of
ethics or decency; "take the bad with the good"