IPA: /ˌmɛɡəˈspɔrændʒiəm/
KK: /mɛgəˈspɔrændʒiəm/
A part of a plant that creates large spores, which are involved in reproduction.
The megasporangium is essential for the development of female gametophytes in certain plants.
Megasporangium → It is formed from "mega-" (from Greek "megas", meaning large) and "sporangium" (from Greek "spora", meaning seed, and "angeion", meaning vessel). The word refers to a large vessel that produces seeds or spores.
Think of 'large' ('mega-') and a 'vessel for seeds' ('sporangium') — that's what a megasporangium is, a large container for producing seeds.