Learn how to say Monocotyledoneae correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word monocotyledon:
a flowering plant with an embryo that bears a single cotyledon (seed leaf). Monocotyledons constitute the smaller of the two great divisions of flowering plants, and typically have elongated stalkless leaves with parallel veins (e.g. grasses, lilies, palms). Compare with dicotyledon.
Class Monocotyledoneae (or -donae, -dones; sometimes Liliopsida), subdivision Angiospermae