si·ren·oi·dei \ˌsīrə̇ˈnȯidēˌī\noun plural alsosi·ren·oi·dea\-ēə\ Usage: capitalized Etymology: New Latin, from Latin siren + New Latin -oidei, -oidea in some classifications: a group of lungfishes containing the genera Neoceratodus and Lepidosiren and some extinct forms from the Mesozoic