The Collaborative International Dictionary of English v.0.48:

Agnate \Ag"nate\, a. [L. agnatus, p. p. of agnasci to be born in
   addition to; ad + nasci (for gnasci) to be born. Cf.
   Adnate.]
   1. Related or akin by the father's side; also, sprung from
      the same male ancestor; as, agnate brother: a brother
      having the same father, but a different mother; in ths
      sense it is a correlative of uterine.
      [1913 Webster]

   2. Allied; akin. "Agnate words." --Pownall.
      [1913 Webster]

            Assume more or less of a fictitious character, but
            congenial and agnate with the former. --Landor.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Agnate \Ag"nate\, n. [Cf. F. agnat.] (Civil Law)
   A relative whose relationship can be traced exclusively
   through males.
   [1913 Webster]

WordNet (r) 3.0 (2006):

agnate
    adj 1: related on the father's side; "a paternal aunt" [syn:
           agnate, agnatic, paternal]
    n 1: one related on the father's side [syn: agnate,
         patrikin, patrilineal kin, patrisib, patrilineal
         sib]

Moby Thesaurus II by Grady Ward, 1.0:

50 Moby Thesaurus words for "agnate":
   affiliated, affinal, affinitive, akin, alike, allied, analogous,
   avuncular, closely related, cognate, collateral, comparable,
   congeneric, congenerous, congenial, connate, connatural, connected,
   consanguine, consanguinean, consanguineous, conspecific,
   correlative, corresponding, distantly related, enate, foster,
   genetically related, german, germane, incident, kindred,
   matrilateral, matrilineal, matroclinous, novercal,
   of common source, of the blood, parallel, patrilateral,
   patrilineal, patroclinous, related, related by blood, sib, sibling,
   similar, undifferentiated, uniform, uterine



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

AGNATES. In the sense of the Roman law were those whose propinquity was
connected by males only; in the relation of cognates, one or more females
were interposed.
     2. By the Scotch law, agnates are all those who are related by the
father, even though females intervene; cognates are those who are related by
the mother. Ersk. L. Scot. B. 1, t. 7, s. 4.