passant

形容词 passant:

1. in walking position with right foreleg raised

1. He mentioned en passant that he was going away.
   他顺便提到他要离开的事。

pas.sant

adj.Heraldry （形容词）【纹章学】
Being a beast facing and walking toward the viewer`s left with one front leg raised.
扮兽行走：饰面为野兽并且抬起前腿朝向观看者左边走动

来源：
Middle English
中古英语
from Old French [present participle of] passer [to pass] * see pass
源自 古法语 [] passer的现在分词 [经过] *参见 pass