bad

adj., n., & adv.
—adj. (worse; worst)
1 inferior, inadequate, defective (bad work; a bad driver; bad light).
2 a unpleasant, unwelcome (bad weather; bad news). b unsatisfactory, unfortunate (a bad business).
3 harmful (is bad for you).
4 (of food) decayed, putrid.
5 colloq. ill, injured (am feeling bad today; a bad leg).
6 colloq. regretful, guilty, ashamed (feels bad about it).
7 (of an unwelcome thing) serious, severe (a bad headache; a bad mistake).
8 a morally wicked or offensive (a bad man; bad language). b naughty; badly behaved (a bad child).
9 worthless; not valid (a bad cheque).
10 (badder, baddest) esp. US sl. good, excellent.
—n.
1 a ill fortune (take the bad with the good). b ruin; a degenerate condition (go to the bad).
2 the debit side of an account (pound500 to the bad).
3 (as pl.; prec. by the) bad or wicked people.
—adv. US colloq. badly (took it bad).
Phrases and idioms:
bad blood ill feeling. bad books see BOOK. bad breath unpleasant-smelling breath. bad debt a debt that is not recoverable. bad egg see EGG(1). bad faith see FAITH. bad form see FORM. a bad job colloq. an unfortunate state of affairs. bad mouth US malicious gossip or criticism. bad-mouth v.tr. US subject to malicious gossip or criticism. bad news colloq. an unpleasant or troublesome person or thing. from bad to worse into an even worse state. in a bad way ill; in trouble (looked in a bad way). not (or not so) bad colloq. fairly good. too bad colloq. (of circumstances etc.) regrettable but now beyond retrieval.
Derivatives:
baddish adj. badness n.
Etymology: ME, perh. f. OE baeligddel hermaphrodite, womanish man: for loss of l cf. MUCH, WENCH