Lewis & Short

āmentum, i, n. [ἅμμα, ἅπτω; v. apo], a strap or thong, esp. upon missile weapons, by means of which they were thrown with greater force (cf. amento): amenta, quibus, ut mitti possint, vinciuntur jacula sive solearum lora, Paul. ex Fest. p. 12 Müll.: epistola ad amentum deligata, Caes. B. G. 5, 48 Herz.: inserit amento digitos, Ov. M. 12, 321: amenta torquent, Verg. A. 9, 665: umor jaculorum amenta emollierat, Liv. 37, 41 al.
Rarely, a shoe-string: soleae sine amento, Plin. 34, 6, 14, § 31.