1870 (implied in imploded), back-formation from implosion. Related: Imploding.
Entries linking to implode
implosion n.
"a bursting inward, a sudden collapse," 1829, modeled on explosion, with assimilated form of in- "into, in, on, upon" (from PIE root *en "in").
And to show how entire the neglect and confusion have been, they speak in the same breath of all these explosions, and of the explosion of a mixture of hydrogen and oxygen, the result of which, instead of being a gas or an enlargement of bulk, a positive quantity, is a negative one. It is a vacuum, in a popular sense, because the produce is water. The result is an implosion (to coin a word), not an explosion .... ["Gas-light," Westminster Review, October 1829]
In early use often in reference to effect of deep sea pressures, or in phonetics. Figurative sense is by 1960.
implosive adj.
1876, originally in linguistics, probably from implode on the model of explosive; implosive is attested in French and German from 1860s.