The Collaborative International Dictionary of English v.0.48:
Hebdomadal \Heb*dom"a*dal\, Hebdomadary \Heb*dom"a*da*ry\, a. [L. hebdomadalis, LL. hebdomadarius: cf. F. hebdomadaire.] Consisting of seven days, or occurring at intervals of seven days; weekly. [1913 Webster]WordNet (r) 3.0 (2006):
hebdomadal adj 1: of or occurring every seven days; "a weekly visit"; "weekly paper" [syn: weekly, hebdomadal, hebdomadary]