I think we are getting a little lost here divorcing words from their contexts, so it may be helpful to re-quote Exodus 21:7-11 (RSV) to remind us of what is going on;
'7 “When a man sells his daughter as a slave, she shall not go out as the male slaves do. 8 If she does not please her master, who has designated her[
a] for himself, then he shall let her be redeemed; he shall have no right to sell her to a foreign people, since he has dealt faithlessly with her. 9 If he designates her for his son, he shall deal with her as with a daughter. 10 If he takes another wife to himself, he shall not diminish her food, her clothing, or her marital rights. 11 And if he does not do these three things for her, she shall go out for nothing, without payment of money.'
So the "master" being the person the daughter is *transferered* to decides whether she be "designated" as a wife for either "for himself" or "for his son", but if she was a free woman why is it not up to her to decide whether she prefers to marry the man or his son? Why is it up to "her master" to decide who she marrys?