WordNet sense 1 (a long wooden bench with a back):

settee

WordNet sense 2 (go under):

sink, go down, go under

WordNet sense 3 (settle into a position, usually on a surface or ground):

settle down

WordNet sense 4 (sink down or precipitate):

subside

WordNet sense 5 (fix firmly):

ensconce

WordNet sense 6 (get one's revenge for a wrong or an injury):

get back

WordNet sense 7 (come to terms):

conciliate, reconcile, make up, patch up

WordNet sense 8 (settle conclusively; come to terms):

determine, square up, square off

WordNet sense 9 (bring to an end; settle conclusively):

adjudicate, decide, resolve, resolve

WordNet sense 10 (make final; put the last touches on; put into final form):

finalize, finalise, nail down

WordNet sense 11 (become settled or established and stable in one's residence or life style):

root, steady down, take root

WordNet sense 12 (take up residence and become established):

locate

WordNet sense 13 (come as if by falling):

descend, fall