Feminine plural from garar; the throat (as used in rumination) -- neck.
see HEBREW garar
H1621. gargeroth
גַּרְגְּרוֺת noun feminine plural neck (on formation compare BaNB 204) — גַּרְגְּרֹתֶ֑יךָ Proverbs 1:9; 3:22, גַּרְגְרוֺתֶ֑ךָ 3:3, גַּרְגְּרֹתֶ֑ךָ 6:21 — always in figure, instruction of parents an ornament, a chain upon neck 1:9, bind them upon thy neck 6:21; so of mercy & truth 3:3, compare 3:22.