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Related to monotrematous: Monotremata
Any of various egg-laying mammals of the order Monotremata of Australia and New Guinea, whose only living members are the platypus and the echidnas.
[From New Latin Monotrēmata, order name : mono- + Greek trēma, trēmat-, perforation (from the fact that they have a single cloaca rather than an anus separate from genital and urinary orifices, as in placental mammals and marsupials); see terə- in Indo-European roots.]
mon′o·trem′a·tous (-trĕm′ə-təs) adj.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.