Definition of poopy suit in US English:

poopy suit

(also poopie suit)

noun

US
military slang
  • A one-piece garment providing protection for the whole body against the cold, wet, etc.

Origin

1950s; earliest use found in James A. Michener (1907–1997), novelist. From a first element of uncertain origin + suit.

Pronunciation

poopy suit

/ˈpuːpi s(j)uːt/