Rare term for rugby; the standard modern word is ラグビー. This kanji spelling is seldom used outside historical or stylistic contexts.
See also: ラグビー
闘球 is an old way of writing rugby, and is hardly used today.
A kanji compound formed from 闘 (fight) and 球 (ball), likely coined as a direct translation of 'rugby football'. The exact origin is uncertain, but it follows the pattern of early 20th-century sport terms.