The Collaborative International Dictionary of English v.0.48:

Fatherhood \Fa"ther*hood\, n.
   The state of being a father; the character or authority of a
   father; paternity.
   [1913 Webster]

WordNet (r) 3.0 (2006):

fatherhood
    n 1: the kinship relation between an offspring and the father
         [syn: fatherhood, paternity]
    2: God when considered as the first person in the Trinity; "hear
       our prayers, Heavenly Father" [syn: Father, Father-God,
       Fatherhood]
    3: the status of a religious leader
    4: the status of a father

Moby Thesaurus II by Grady Ward, 1.0:

40 Moby Thesaurus words for "fatherhood":
   affiliation, agnation, alliance, ancestry, blood,
   blood relationship, brotherhood, brothership, cognation,
   common ancestry, common descent, connection, consanguinity,
   cousinhood, cousinship, enation, fatherliness, filiation,
   fraternity, kindred, kinship, maternity, matrilineage, matriliny,
   matrisib, matrocliny, motherhood, paternalness, paternity,
   patrilineage, patriliny, patrisib, patrocliny, propinquity,
   relation, relationship, sibship, sisterhood, sistership,
   ties of blood