The Collaborative International Dictionary of English v.0.48:

Handmaid \Hand"maid`\ (h[a^]nd"m[=a]d`), Handmaiden
\Hand"maid`en\ (h[a^]nd"m[=a]d`'n), n.
   A maid that waits at hand; a female servant or attendant.
   [WordNet sense 2]
   [1913 Webster]

   2. Something or someone serving in a subordinate position;
      as, theology should be the handmaiden of ethics. [WordNet
      sense 1]

   Syn: handmaid, servant.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

handmaiden
    n 1: in a subordinate position; "theology should be the
         handmaiden of ethics"; "the state cannot be a servant of
         the church" [syn: handmaid, handmaiden, servant]
    2: a personal maid or female attendant [syn: handmaid,
       handmaiden]