1867, from Swedish dynamit, coined 1867 by its inventor, Swedish chemist Alfred Nobel (1833-1896), from Greek dynamis "power" (see dynamic (adj.)) + -ite (2). Figurative sense of "something potentially dangerous" is from 1922. Positive sense of "dynamic and excellent" by mid-1960s, perhaps originally African-American vernacular.
1881, from dynamite (n.). Related: Dynamited; dynamiting.