Plain English Meaning

An airplane built to operate off water instead of, or in addition to, a runway.

Full Definition

An airplane designed to take off from and land on water, equipped with either floats (a floatplane) or a watertight hull (a flying boat) in place of, or in addition to, conventional landing gear.

Context Anchor

You will see this term in seaplane training, water operations, aircraft category and class discussions, and chapters covering takeoffs, landings, taxiing, docking, and beaching on water.

Derivation

A straightforward compound of 'sea' and 'plane.' Worth noting: 'sea' here is used loosely — routinely operate from lakes and rivers, not just the sea.