The Collaborative International Dictionary of English v.0.48:

Waiting \Wait"ing\,
   a. & n. from Wait, v.
   [1913 Webster]

   In waiting, in attendance; as, lords in waiting. [Eng.]

   Waiting gentlewoman, a woman who waits upon a person of
      rank.

   Waiting maid, Waiting woman, a maid or woman who waits
      upon another as a personal servant.
      [1913 Webster]