From the same as ro'sh; the first, in place, time, order or rank (specifically, a firstfruit) -- beginning, chief(-est), first(-fruits, part, time), principal thing.
see HEBREW ro'sh
H7225. reshith
[רֵאשִׁית] noun feminine beginning, chief (for *רְאֵשִׁית NöGGA 1884, 1019, compare HolzHexateuch 465; Syriac ); — absolute ׳ר Deuteronomy 33:21+, construct ׳ר Genesis 10:10+, רֵשִׁית Deuteronomy 11:12; suffix רֵאשִׁיתוֺ Ecclesiastes 7:8, רֵאשִׁתוֺ Job 42:12, etc.; —
1.a beginning of kingdom Genesis 10:10 (J), year Deuteronomy 11:12, reign Jeremiah 26:1; 27:1; 28:1; 49:34;= first phase, step, or element in course of events Isaiah 46:10 (opposed to אַחֲרִית); of a thing (דָּבָר) Ecclesiastes 7:8 (opposed to id.); of sin Micah 1:13, strife Proverbs 17:14, wisdom Psalm 111:10, knowledge Proverbs 1:7 thy beginning Job 8:7 +?his beginning 42:12 (both opposed to אַחֲרִית), ׳ר before clause, ׳בְּר א ׳בָּרָא Genesis 1:1 in the beginning when god created (> absolute in the beginning God created); ׳ר אֹנִי 49:3 (poem) beginning (first product) of my manly vigour ("" כֹּחִי בְּכֹרִי so Deuteronomy 21:17; Psalm 78:51 (both "" בְּכוֺת 105:36; compare ׳ר אֵל דֵּרְכֵי Job 40:19 (of hippopotamus), ׳ר דַּרְכּוֺ Proverbs 8:22 (of wisdom);=first season (of a tree) Hosea 9:10; גּוֺיִם׳ר Numbers 24:20 (JE), first, earliest, of nations.
b. first of fruits Exodus 23:19 (E), 34:26 (JE), Deuteronomy 26:2, 10; Ezekiel 44:30.a, of harvest Leviticus 23:10 (H), grain Deuteronomy 18:4; 2 Chronicles 31:5 dough Numbers 15:20-21, (P), Ezekiel 44:30b Nehemiah 10:38, wool Deuteronomy 18:4; of כָּלתְּֿבוּאָתֶ֑ךָ Proverbs 3:9; Israel is ׳ר תְּבוּאָתֹה Jeremiah 2:3 (i.e. of ׳יs increase); ׳ר=first-fruits Leviticus 2:12 (P), Numbers 18:12 (P), Nehemiah 12:44; ׳ר הָאָרֶץ Ezekiel 48:14
2 first chief, Amos 6:1; ׳ר גְּבוּרָתָם Jeremiah 49:35 (of bows); so apparently ׳ר עַמּוֺן בְּנֵי Daniel 11:41, i.e. the principal part of them (Buhl Marti conjecture שְׁאֵרִית after ᵑ6); ׳ר מַשְׁאוֺתֵיכֶם Ezekiel 20:40, i.e. your chief oblations; ׳ר שְׁמָנִים Amos 6:6, i.e. choice oils; = choice part, of land Deuteronomy 33:21, offering 1 Samuel 2:29, הַחֵרֶם 15:21; absolute chief thing Proverbs 4:7 (of wisdom).