hitchhiker; person who catches a ride
Refers to someone who gets a free ride in someone else's vehicle, typically by thumbing a lift. The cross-reference to ヒッチハイカー suggests a similar meaning.
See also: ヒッチハイカー
A hitchhiker was sticking out their thumb at the highway entrance.
He traveled as a hitchhiker to save on travel expenses.
Compound of 便乗 (びんじょう, 'taking advantage of a ride') + 者 (しゃ, 'person'). The exact historical derivation is uncertain, but the word follows a common pattern for forming agent nouns.