やばい

Etymology
Originally a slang term used in the criminal underworld,  used to indicate that the police were getting close. First cited to a text from 1892.

Derived as a shift to an -i adjective of older -na adjective, itself a slang term of uncertain derivation that appears in sources from the late 1700s.

Possibly related to the ayabu- stem in, and the ayau- stem in.

Adjective

 * 1)  dangerous, risky
 * 2)  risque, off-color, vulgar
 * 3)  highly concerning
 * 4)  very good, awesome, crazy, sick, wild
 * 1)  very good, awesome, crazy, sick, wild
 * 1)  very good, awesome, crazy, sick, wild

Interjection

 * 1) oh no, crap