The Collaborative International Dictionary of English v.0.48:

Maternal \Ma*ter"nal\, a. [F. maternel, L. maternus, fr. mater
   mother. See Mother.]
   Of or pertaining to a mother; becoming to a mother; motherly;
   as, maternal love; maternal tenderness.
   [1913 Webster]

   Syn: See Motherly.
        [1913 Webster]

WordNet (r) 3.0 (2006):

maternal
    adj 1: characteristic of a mother; "warm maternal affection for
           her guest"- Dorothy Sayers [ant: paternal]
    2: relating to or derived from one's mother; "maternal genes"
    3: relating to or characteristic of or befitting a parent;
       "parental guidance" [syn: parental, maternal, paternal]
       [ant: filial]
    4: related on the mother's side; "my maternal grandmother" [syn:
       enate, enatic, maternal(p)]

Moby Thesaurus II by Grady Ward, 1.0:

43 Moby Thesaurus words for "maternal":
   adoring, affectionate, ancestorial, ancestral, caring, conjugal,
   demonstrative, devoted, doting, faithful, fatherlike, fatherly,
   filial, fond, grandfatherly, grandmotherly, grandparental,
   husbandly, kind, kindly, languishing, lovelorn, lovesick, lovesome,
   loving, maternalistic, melting, mother, motherlike, motherly,
   nurturing, parent, parental, paternal, patriarchal, romantic,
   sentimental, soft, tender, understanding, uxorious, warm, wifely



Bouvier's Law Dictionary, Revised 6th Ed (1856):

MATERNAL. That which belongs to, or comes from the mother: as, maternal
authority, maternal relation, maternal estate, maternal line. Vide Line.