I. ˈ ̷ ̷ˌ ̷ ̷ noun
( -s )
Etymology: from melt down, v.
: the process or course of melting something (as scrap metal or ice cream)
II. noun
1. : the accidental melting of the core of a nuclear reactor
2. : a rapid or disastrous decline or collapse
3. : a breakdown of self-control (as from fatigue or overstimulation)