v.
在进行中, 顺道

En passant \En` pas`sant"\ [F.]
In passing; in the course of any procedure; -- said specif.
(Chess), of the taking of an adverse pawn which makes a first
move of two squares by a pawn already so advanced as to
threaten the first of these squares. The pawn which takes en
passant is advanced to the threatened square.
[Webster 1913 Suppl.]