'Undergarments' in the Bible

The priest is to put on his linen robe, and he shall put on undergarments next to his flesh; and he shall take up the ashes to which the fire reduces the burnt offering on the altar and place them beside the altar.

He shall put on the holy linen tunic, and the linen undergarments shall be next to his body, and he shall be girded with the linen sash and attired with the linen turban (these are holy garments). Then he shall bathe his body in water and put them on.