Callisthenics vs. Calisthenics: What's the Difference?

Variant of calisthenics.

(used with a pl. verb) Gymnastic exercises designed to develop muscular tone and promote physical well-being

Alternative spelling of calisthenics

(used with a sing. verb) The practice or art of such exercises

Light exercise designed to promote general fitness

(in the plural) Gymnastic exercises under the participation of a (surface-wise) multitude of muscles and often minimal equipment (thus, usually bodyweight exercises) with a stress on stamina.

(in the singular) A system of such exercises.

The science, art, or practice of healthful exercise of the body and limbs, to promote strength, gracefulness, and general fitness; light gymnastics.

Light exercise designed to promote general fitness