heavy

Heavy is an English adjective used to describe objects or concepts that have a large mass or exert a strong gravitational force, or that are characterized by great intensity or severity. In everyday language, something described as heavy is difficult to lift or move, or a situation is said to be heavy if it feels burdensome or serious.

In physics, weight is the force due to gravity acting on mass, so heavy typically implies a large weight relative to something similar. Mass itself is invariant, while weight depends on gravity. The term also appears in specialized contexts: heavy water (D2O), which contains deuterium; heavy isotopes refer to atoms with more neutrons than the most common form; heavy metals are a class of elements with high density and atomic weight; while many heavy metals are hazardous in environmental exposure, not all heavy metals are toxic.

Heavy is used in materials and labor contexts: heavy equipment and heavy machinery refer to large, powerful devices for construction and mining; heavy lift operations involve moving very large loads.

In culture and media, heavy is a common descriptor for music and art that emphasizes forceful, dense, or distorted sound—especially in the genre known as heavy metal—and it is also used as a title for various songs and films.

Etymology traces to Old English hefig meaning “laden” or “burdened,” reflecting the term’s long association with weight and weightiness.