monogamist
noun
mo·nog·a·mist mə-ˈnä-gə-mist 
: one who practices or upholds monogamy
Example Sentences
Recent Examples on the Web The title characters are complementary types: Fiona is an outgoing serial monogamist and a law-school dropout, Jane an insecure budding author who struggles with her bisexuality. 
Los Angeles Times, 3 Jan. 2022 As if having to hear her ill-informed take on coronavirus wasn't enough, Kelly annoyingly ends the episode by first suggesting Elizabeth try being a serial monogamist like her, and then throwing her in the pool. Marcus Jones, EW.com, 26 Nov. 2020 This is extremely hard for me as a serial monogamist. Love Letters.com, 30 Mar. 2020 Ezra Shaw/Getty Images PEBBLE BEACH, Calif. — Gary Woodland grew up a serial monogamist, in love, depending on the season, with basketball, baseball and golf. Karen Crouse, New York Times, 17 June 2019 After all, even die-hard monogamists tend to feel pangs of desire for others. Tara Struyk, Glamour, 1 Feb. 2018
Los Angeles Times, 3 Jan. 2022 As if having to hear her ill-informed take on coronavirus wasn't enough, Kelly annoyingly ends the episode by first suggesting Elizabeth try being a serial monogamist like her, and then throwing her in the pool. Marcus Jones, EW.com, 26 Nov. 2020 This is extremely hard for me as a serial monogamist. Love Letters.com, 30 Mar. 2020 Ezra Shaw/Getty Images PEBBLE BEACH, Calif. — Gary Woodland grew up a serial monogamist, in love, depending on the season, with basketball, baseball and golf. Karen Crouse, New York Times, 17 June 2019 After all, even die-hard monogamists tend to feel pangs of desire for others. Tara Struyk, Glamour, 1 Feb. 2018 Word History
First Known Use
circa 1721, in the meaning defined above
Medical Definition
monogamist
noun
mo·nog·a·mist mə-ˈnäg-ə-məst
: a person who practices or upholds monogamy