Definition of boundary layer
: a region of fluid (such as air) moving relative to a nearby surface (such as that of an airplane wing) that is slowed by the viscosity of the fluid and its adhesion to the surface
First Known Use of boundary layer
Learn More about boundary layer
Britannica.com: Encyclopedia article about boundary layer
Seen and Heard
What made you want to look up boundary layer? Please tell us where you read or heard it (including the quote, if possible).