HEBDOMAD
week, hebdomad
(noun) any period of seven consecutive days; “it rained for a week”
Source: WordNet® 3.1
Etymology
Noun
hebdomad (plural hebdomads)
(obsolete) A group of seven.
A period of seven days; a week.
(Gnosticism) A group of seven world-creating archons (supernatural beings) often regarded as somewhat hostile; also, a term of address for the Demiurge.
Source: Wiktionary
Heb"do*mad, n. Etym: [L. hebdomas, -adis, Gr. "ebdoma`s the number
seven days, fr. Seven.]
Definition: A week; a period of seven days. [R.] Sir T. Browne.
Source: Webster’s Unabridged Dictionary 1913 Edition