The Collaborative International Dictionary of English v.0.48:

Amniotic \Am`ni*ot"ic\, a. [Cf. F. amniotique.] (Anat.)
   Of or pertaining to the amnion; characterized by an amnion;
   as, the amniotic fluid; the amniotic sac.
   [1913 Webster]

   Amniotic acid. (Chem.) [R.] See Allantoin.
      [1913 Webster] Amoeba

WordNet (r) 3.0 (2006):

amniotic
    adj 1: of or related to the amnion or characterized by
           developing an amnion; "amniotic membrane" [syn:
           amniotic, amnionic, amnic]