σάκκος also written σάκος, -ου, ὁ
(cf. Heb.שַׂק, which it renders in LXX),
1. a coarse cloth, sackcloth, usually made of hair: Re 6:12.
2. Anything made of sackcloth;
(a) a sack (Ge 42:25, al.);
(b) a garment of sackcloth, expressive of mourning or penitence: Mt 11:21, Lk 10:13, Re 11:3.†