The Collaborative International Dictionary of English v.0.48:
Seventy \Sev"en*ty\, n.; pl. Seventies. 1. The sum of seven times ten; seventy units or objects. [1913 Webster] 2. A symbol representing seventy units, as 70, or lxx. [1913 Webster] The Seventy, the translators of the Greek version of the Old Testament called the Septuagint. See Septuagint. [1913 Webster]