As verbs the difference between alienate and ostracize
is that alienate is to convey or transfer to another, as title, property, or right; to part voluntarily with ownership of while ostracize is to exclude (a person) from society or from a community, by not communicating with them or by refusing to acknowledge their presence; to refuse to talk to or associate with; to shun.
As a adjective alienate
is estranged; withdrawn in affection; foreign; with from .
As a noun alienate
is (obsolete) a stranger; an alien.