The Collaborative International Dictionary of English v.0.48:
Seventh \Sev"enth\, a. [From Seven: cf. AS. seofo[eth]a.]
1. Next in order after the sixth;; coming after six others.
On the seventh day, God ended his work which he had
made; and he rested on the seventh day from all his
work which he had made. --Gen. ii. 2.
2. Constituting or being one of seven equal parts into which
anything is divided; as, the seventh part.
Seventh day, the seventh day of the week; Saturday.
Seventh-day Baptists. See under Baptist.