An alternative or less common form meaning the same as calisthenic; relating to exercises that strengthen the body without equipment.
From calisthenic plus additional -al suffix, creating a doubly-suffixed adjective; represents an older or more formal variant of the standard term.
The -al variant is more archaic—you'd be unlikely to hear 'calisthenical' today, but it shows how English sometimes adds extra suffixes to Greek roots, occasionally creating redundancy.
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