calisthenics

This term describes a specific discipline of fitness that relies on gravity and body weight rather than external machinery or weights. It carries a connotation of agility and functional strength, often associated with military training or gymnastics, emphasizing a lean and athletic physique over bulk.

Grammatically, the word is a mass noun that ends in s but is treated as singular in construction, similar to mathematics or athletics. Because it is uncountable, it does not have a plural form and cannot be used with a count modifier; instead, one would refer to a specific session as a calisthenics workout or a routine of calisthenics.