Home›Browse›M›monotrememonotremeOur editors are putting together more complete content — check back in about 20 minutesmonotrememonotreme — nounnoun1. a mammal that lays eggs, like the platypus or echidna1.nounDefinitiona mammal that lays eggs, like the platypus or echidnaExampleMonotremes are very unusual mammals that lay eggs instead of giving birth to live young.