8478 tachath takh'-ath
from the same as 8430; the bottom (as depressed); only adverbially, below (often with prepositional prefix underneath), in lieu of, etc.:--as, beneath, X flat, in(-stead), (same) place (where...is), room, for...sake, stead of, under, X unto, X when...was mine, whereas, (where-)fore, with.
See H08430.