Source : Webster's Revised Unabridged Dictionary (1913)

Hebdomad \Heb"do*mad\, n. [L. hebdomas, -adis, Gr. "ebdoma`s the
   number seven days, fr. ? seventh, ? seven. See {Seven}.]
   A week; a period of seven days. [R.] --Sir T. Browne.

Source : WordNet®

hebdomad
     n : any period of seven consecutive days; "it rained for a week"
         [syn: {week}]