"roof" radical (Kangxi radical 40), occurring in 家, 定, 安 etc, referred to as 寶蓋|宝盖[bao3 gai4]
宀
=
丶
+
冖
:
Mnemonic symbol: the strokes of this character look like a graduation cap (宀). Marilyn Monroe (mi-) wants to go to the anthill after her graduation from university. In the anthill's kitchen (an2), her friends snatch away her graduation cap (宀), and instead put a cooking top (冖) and a petal leaf (丶) on her head.