From atsah; the spine (as giving firmness to the body) -- backbone.
see HEBREW atsah
H6096. atseh
עָצֶה noun [masculine] either spine or os sacrum, bone close to fat-tail, ׳הֶע Leviticus 3:9.
IV. עצה (√ of following; LagBN 157 compare a land abounding with the trees called ).