Open relationships are committed but not exclusive in terms of sex. Polyamory is committed but not exclusive in terms of love and/or sex and/or commitment. The language of non-monogamy is rather beautifully alive and undecided at the moment.

Is an open relationship non-monogamous?

Open relationships fall under the larger category of consensually non-monogamous relationships. They are relationships in which one or both partners can pursue sex, and sometimes emotional attachments, with other people.