ナイター (naitā) means “night game” | MotiTan Japanese Dictionary

More examples

野球場ではナイターの照明が明るく輝いています。ya kyū jō de wa na i tā no shō mei ga aka ru ku kagaya i te i ma su

The lights for the night game shine brightly at the baseball stadium.

Describes a sporting event played at night, with the time of play as its defining feature rather than the sport itself.

夜間に行われるスポーツの試合。ya kan ni okona wa re ru su pō tsu no shi ai

ナイター (naitā) is a Japanese coinage based on the English form nighter, built from night with the ending -er for a game held at night.

English normally uses night game rather than nighter for this meaning, so ナイター (naitā) is a Japan-specific term despite its English-looking form.