Or shilshom {shil-shome'}; from the same as Shelesh; trebly, i.e. (in time) day before yesterday -- + before (that time, - time), excellent things (from the margin), + heretofore, three days, + time past.
see HEBREW Shelesh
H8032. shilshowm
שִׁלְשֹׁם and (less often) שִׁלְשׁוֺם25
adverb = three days ago, specifically day before yesterday (Köii. 1. 255 f. LagBN 20 Anm. BaNB § 216 b); — in phrase שׁ ׳תְּמוֺל Exodus 5:8 yesterday (and) day before, idiomatic for hitherto, so Ruth 2:11, שׁ ׳אֶתְמוֺל 1 Samuel 4:7; ׳כִּת ׳שׁ Genesis 31:2, 5 (E), Exodus 5:7, 14 (J), 2 Kings 13:5, compare 1 Samuel 14:21; 19:7; ׳גַּםתֿ ׳גַּםשֿׁ Exodus 4:10 (J), 2 Samuel 3:17; 1 Chronicles 11:2, compare 2 Samuel 5:2; ׳מִתּ ׳שׁ from aforetime, previously Exodus 21:29, 36 (E), Deuteronomy 4:42; 19:4, 6; Joshua 4:18 (J), 3:4; 20:5 (both R), compare 1 Samuel 10:11; ׳כִּת ׳שׁ 21:6 as formerly (but Bu ׳מִתּ ׳שׁ = for some days). — ׳שׁ Proverbs 22:20 Kt is difficult; Qr שָׁלִשִׁים (see III. שָׁלִישׁ) is impossible; supply perhaps תְּמוֺל have I not thee heretofore, etc.?