egg-laying mammal egg laying • eggler · · · Info · Definitions · Synonyms · Characters · · egg-laying mammal · · Text Common · · Latin · · Scripts 17 · · Length 5 · · Syllables Definitions · · · (noun) the most primitive mammals comprising the only extant members of the subclass Prototheria. Synonyms: monotreme, egg-laying mammal. · · Noun Definition 1 Synonyms · · · monotreme · · Synonym 1 Characters · · space U+0020 - hyphen-minus U+002D a latin small letter a U+0061 e latin small letter e U+0065 g latin small letter g U+0067 i latin small letter i U+0069 l latin small letter l U+006C m latin small letter m U+006D n latin small letter n U+006E y latin small letter y U+0079