Definition of Bad

Adjective: bad (worse,worst) bad

Having undesirable or negative qualities
"a bad report card"; "his sloppy appearance made a bad impression"; "a bad little boy"; "clothes in bad shape"; "a bad cut"; "bad luck"; "the news was very bad"; "the reviews were bad"; "the pay is bad"; "it was a bad light for reading"; "the movie was a bad choice"
Very intense
"a bad headache"; "had a bad shock"; "a bad earthquake"; "a bad storm";
- big
Feeling physical discomfort or pain ('tough' is occasionally used colloquially for 'bad')
"my throat feels bad"; "she felt bad all over";
- tough
(of foodstuffs) not in an edible or usable condition
"bad meat";
- spoiled, spoilt
Feeling or expressing regret or sorrow or a sense of loss over something done or undone
"he felt bad about breaking the vase";
- regretful, sorry
Not capable of being collected
"a bad debt";
- uncollectible
Below average in quality or performance
"a bad chess player"; "a bad recital"
(linguistics) nonstandard
"so-called bad grammar"
Not financially safe or secure
"a bad investment";
- risky, high-risk, speculative
Physically unsound or diseased
"has a bad back"; "a bad heart"; "bad teeth";
- unfit, unsound
Capable of harming
"bad air"; "smoking is bad for you"
Characterized by wickedness or immorality
"led a very bad life"
Reproduced fraudulently
"like a bad penny...";
- forged
Not working properly
"a bad telephone connection";
- defective

Noun: bad bad

That which is below standard or expectations as of ethics or decency
"take the bad with the good";
- badness

Adverb: bad bad

With great intensity ('bad' is a nonstandard variant for 'badly')
"it hurts bad"; "we need water bad";
- badly
Very much; strongly
"he wants a bicycle so bad he can taste it";
- badly