From The Collaborative International Dictionary of English v.0.48 [gcide]:
Authorship \Au"thor*ship\, n.
1. The quality or state of being an author; function or
dignity of an author.
[1913 Webster]
2. Source; origin; origination; as, the authorship of a book
or review, or of an act, or state of affairs.
[1913 Webster]
From WordNet (r) 3.0 (2006) [wn]:
authorship
n 1: the act of creating written works; "writing was a form of
therapy for him"; "it was a matter of disputed authorship"
[syn: writing, authorship, composition, penning]
2: the act of initiating a new idea or theory or writing; "the
authorship of the theory is disputed" [syn: authorship,
paternity]