Specifically, this is definition of "heavy" from the FAA Airmans Information Manual:


Aircraft Classes
For the purposes of Wake Turbulence Separation Minima, ATC classifies aircraft as Heavy, Large, and Small as follows:

(a) Heavy-Aircraft capable of takeoff weights of more than 255,000 pounds whether or not they are operating at this weight during a particular phase of flight.

(b) Large-Aircraft of more than 41,000 pounds, maximum
certificated takeoff weight, up to 255,000 pounds.

(c) Small-Aircraft of 41,000 pounds or less maximum certificated takeoff weight

"Heavy" is always used as part of a flights call sign when the aircraft meets the criteria. The term most often applies to widebody aircraft as narrowbodies seldom make that weight limit.

However there is a noteable exception:

Prior to the introduction of the Boeing 757, the cut off weight was 300,000lbs. However it was lowered after a series of wake turbulence accidents and incidents involving the B757 as the leading aircraft, the landing separation standards were modified in 1996 by creating a new category just for the B757. The new weight cut-off for Heavy aircraft was set at 255,001 lbs. In the Fall of 1996, a stretch version of the B757-200 was introduced: the B757-300 series, which had the same wingspan as the B757-200 (124.8 ft). Due to the extended fuselage, the maximum takeoff weight (270,000 lbs) was no longer within the weight limits for the B757 class and so the "large" class narrowbody B757-300 is considered a "heavy" class. Due to the unique characteristics of the 757, for wake turbulence separation all models of the airliner are treated as "heavies" even if they don't meet the weight requirement.

A term used for the larger commercial aircraft auch as B747s and A340s. Because Heavy aircraft leave larger wake vortexes behind them, they need to be separated more from medium aircraft such as A320 and B737 and even more from light aircraft.

Not this question.

a bouncer or bodyguard

This is The Heavy...

Burden ...

A bad guy in a crime movie, or a really big airplane.

My fatty cat. She weights 16 pounds, although in a current diet.

A fat chick.

a fully loaded commerial aircraft