seat

command, headquarters

backside, behind, bottom, breech, bum, buns, butt, buttocks, can, cheeks, derriere (or derrière), duff, fanny, hams, haunches, hunkers, posterior, rear, rear end, rump, tail, tail end

axis, base, capital, center, central, core, cynosure, epicenter, eye, focus, ground zero, heart, hub, locus, mecca, navel, nerve center, nucleus

set down, sit

baptize, inaugurate, induct, initiate, install, instate, invest