えんすい· also まるぎり
cone; round gimlet
Also written 円すい、丸錐
Noun
まん丸まるに見みえるあのお月つきさまはね、実じつは円錐えんすいの底面ていめんなんだよ。
The moon looks so perfectly round. It's actually the base of a cone, you know.