There are several synonyms for the phrase "put an end to", including "stop", "halt", "cease", "terminate", "finish", "conclude" and "abolish". Each of these words implies the act of bringing something to a close or an end. For example, "stop" suggests a sudden break or a cessation of an activity or event, while "halt" has a more deliberate connotation. "Cease" suggests a complete and permanent end to something, while "terminate" implies an official conclusion. "Finish", "conclude" and "abolish" all imply a sense of achieving a final outcome, with "abolish" having the added connotation of ending something for moral or political reasons.