noun
implosion
im-PLOH-zhun/ɪmˈpləʊʒn/
A collapse directed inward.
The controlled implosion brings the old building down within seconds.

Etymology
Modeled on explosion, the word uses the inward prefix to picture a burst directed inward—a sudden collapse. The same image extends figuratively to a collapse or failure that is not physically a bursting event.
In context
so what exactly is an implosion and how does this occur within submarines the simple answer is it is literally the opposite of an explosion so this is when an object collapses in on itself in milliseconds
More examples
- A vacuum inside the tank causes an implosion.
- Months of infighting lead to the committee's implosion.
- Engineers study implosions to understand how structures collapse inward.
Forms
implosion · implosions
implode verb — To collapse inward or fail internally.
Similar words
- collapse
- Does not specify whether movement is inward or downward.
- cave-in
- Usually involves a roof or ground collapsing into a cavity.