en passant

Turtle doves have long been celebrated for their fidelity; and this turtle dove, though he flirts, en paſſant, with a ſky-lark, a jay, and a quail, does not materially diſcredit the famed conſtancy of his ſpecies, theſe birds being all coquettes: but when he meets (as he fortunately does) with an amiable dove-mate, he is as faithful as any turtle, of any grove.

[I]f the opponent chooses to make this capture, he must do it immediately on his next move – if he makes any other move on his next move, he forever loses the chance to capture that pawn en passant, though he still retains the right to capture another pawn en passant should a similar situation arise elsewhere.