From gymnastic: see -ics; from Latin gymnasticus, from Ancient Greek γυμναστικός (gumnastikós), from γυμναστής (gumnastḗs, “athlete, gymnast”), from γῠμνᾰ́ζω (gŭmnắzō, “to train, exercise”), from γυμνός (gumnós, “naked”), because Greek athletes trained naked. By surface analysis, gymnast + -ics.