monogamous

/məˈnɑɡəməs/
adjective
  1. Having only one spouse or sexual partner at a time; practicing monogamy.
    • Many bird species are monogamous, staying with the same mate for life.
    • In a monogamous marriage, both partners agree to be faithful to each other.
    • They are in a monogamous relationship and have been together for ten years.
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