From shaqaq; properly, a mesh (as allowing a liquid to run through), i.e. Coarse loose cloth or sacking (used in mourning and for bagging); hence, a bag (for grain, etc.) -- sack(-cloth, -clothes).
see HEBREW shaqaq
H8242. saq
שַׂק noun masculineJoshua 9:4 sack, sackcloth (see SchwZAW xi (1891), 173 who conjectures Egyptian origin; Late Hebrew סַק sackcloth (rare); Assyrian ša‡‡u, sack (DlHWB 687 a), sackcloth (WklAltor. Forsch, vi. 44); Ethiopic = Biblical Hebrew; Aramaic סַקָּא, ; Greek σάκκος LewyFremdw. 87); — absolute ׳שׂ Genesis 37:34 +, שָׂ֑ק Jeremiah 48:37 +; suffix שַׂקִּי Psalm 30:12, etc.; plural שַׂקִּים Joshua 9:4 +, suffix שַׂקֵּיהֶם Genesis 42:35; —
1 sack, for grain Genesis 42:25, 27 ("" אַמְתַּחַת), 42:35; 42:35 (E), Joshua 9:4 (JE), perhaps also Leviticus 11:32 (P).
2 sackcloth:
a. worn in mourning and humiliation (see NowArchaeology i. 192 f. SACookEncy. Bib. under the word), either loose garment like sack, or piece of similar material (of rough, dark hair), fastened round body: put (שִׂים) on loins Genesis 37:34 (J), 1 Kings 20:31, on (bare) flesh 21:27; 2 Kings 6:30, compare Jeremiah 48:37; Job 16:15 (with תָּפַר); שׂ עַלכָּֿלמָֿתְנַיִם ׳וְהַעֲלֵיתִי Amos 8:10; usually girt on (חָגַר) 2 Samuel 3:31; Isaiah 15:3; 22:12; Jeremiah 4:8; 6:26; 49:3; Ezekiel 7:18; 27:31; 1 Kings 20:32; Joel 1:8, compare Isaiah 3:24; בַּשּׂ ׳כִּסָּה 2 Kings 19:1-2,= Isaiah 37:1-2, Jonah 3:6, 8; 1 Chronicles 21:16, figurative of heavens (compare קָדַר), ׳שׂ כְּסוּתָם אָשִׂים Isaiah 50:3; late שׂ ׳לָבַשׁ put on sackcloth Jonah 3:5; Esther 4:1, compare 4:2; Psalm 35:13; 69:12; וְשׂ ׳בְּצוֺם Nehemiah 9:1, compare Daniel 9:3; שׂ ׳מִּתַּח loosen sackcloth Isaiah 20:2 (+ מֵעַל), Psalm 30:12 (opposed to שִׂמְחָה), שׂ ׳הֵסִיר מֵעַל Esther 4:4.
b. same garment (or material) spread out (to lie on), 2 Samuel 21:10 (with הִטָּה), Isaiah 58:5 (with הִצִּיעַ), compare Esther 4:3 בַּשׂ ׳וַיִּשְׁכַּב 1 Kings 21:27, בַּשּׂ ׳לִינוּ Joel 1:13.