Source : Webster's Revised Unabridged Dictionary (1913)

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.

Source : WordNet®

hebdomadal
     adj : appearing or occurring every seven days; "hebdomadal (or
           weekly) newspapers"; "hebdomadal meetings" [syn: {hebdomadary}]