off-track betting ticket
Refers to a betting ticket purchased at an off-track betting facility (場外馬券売場) rather than at the racecourse itself.
彼は場外馬券売場で馬券を買った。
He bought a betting ticket at the off-track betting facility.
馬券 is a general betting ticket, while 場外馬券 specifically refers to one purchased off-track.
The full term for the off-track betting facility where 場外馬券 are sold.
Compound of 場外 (off-track, outside the venue) and 馬券 (betting ticket).