[אַמָּה] n.f. (etym. & mng. dub.; Thes foundation) only Is 6:4
Strong Concise Dictionary Of The Words In The Hebrew Bible
H520אַמָּהʼammâh; prolonged from 517; properly, a mother (i.e. unit of measure, or the fore-arm (below the elbow), i.e. a cubit; also a door-base (as a bond of the entrance) — cubit, + hundred (by exchange for 3967), measure, post.