Longman Dictionary of Contemporary English
Douglas Harper's Etymology Dictionary
Wiktionary
alt. 1 (context sports English) A pair of games played one after another between the same teams. 2 A pair of top rank events after another, at one venue. 3 (context fishing English) The catching of a single fish simultaneously by two fishermen when fishing together. 4 (context rail English) A train pulled by two locomotives. n. 1 (context sports English) A pair of games played one after another between the same teams. 2 A pair of top rank events after another, at one venue. 3 (context fishing English) The catching of a single fish simultaneously by two fishermen when fishing together. 4 (context rail English) A train pulled by two locomotives.
Usage examples of "double-header".
Imperials, one or two oddities like an unbroken pair or a double-header, the occasional cheap packet of mixed pins on approval .