From the same as gib'ah; a cap (as hemispherical) -- bonnet.
see HEBREW gib'ah
H4021. migbaoth
מִגְבָּעוֺת noun feminine plural head-gear, turban, of common priest (conical? compare Di Exodus 28:40), 28:40 Leviticus 8:13; מִגְבָּעֹת Exodus 29:9; 39:28 (הַמּ ׳מַּאֲרֵי).