en passant

from WordNet (r) 3.0 (2006)

en passant
    adv 1: incidentally; in the course of doing something else; "he
           made this remark in passing" [syn: {in passing}, {en
           passant}]
    n 1: (chess) a chess pawn that is moved two squares can be
         captured by an opponent's pawn commanding the square that
         was passed

from The Collaborative International Dictionary of English v.0.48

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.]