'athleticism' originates from the adjective 'athletic' combined with the suffix '-ism', where '-ism' conveyed the idea of 'practice, characteristic, or system'.

'athletic' ultimately comes from Greek 'athlētikos' (from 'athlētēs', 'contestant'), via Latin and French ('athleticus'/'athlétique'), and English formed 'athletic'; the noun 'athleticism' was later formed in English by adding '-ism' to 'athletic'.

Initially referring specifically to qualities of an 'athlete' or things relating to contests, it evolved to the broader modern sense of 'physical skill, vigor, or the practice/value of athletics.'