ăcus, ūs, f. [cf. 2. acer].
I A needle or pin , as being pointed , both for common use and ornament:“quasarcinatrix veletiam ornatrix utitur,” Paul. ex Fest. p. 9 Müll.
A Lit.: mirabar vulnus, quod acu punctum videtur, Cic. Mil. 24.—Hence, acu pingere, to embroider , Verg. A. 9, 582; Ov. M. 6, 23; cf. Plin. 8, 48, § 191; Isid. Orig. 19, 22, 22.—Esp. a hair-pin : figat acus tortas sustineatque comas, Mart. 14, 24: foramen acūs, the eye of a needle , Vulg. Matt. 19, 24.—Also, a surgeon's needle , a probe , Cels. 7, 17.—Hence,
B Trop.: acu rem tangere, to touch the thing with a needle; in Engl. phrase, to hit the nail on the head , Plaut. Rud. 5, 2, 19; so, to denote careful and successful effort: si acum quaereres, acum invenisses, id. Men. 2, 1, 13.—
II The tongue of a buckle , Treb. Poll. Claud. 14.—
III I. q. acus, ĕris, Col. 2, 10, 40.—
IV An implement of husbandry , Pall. 1, 43, 2.