How to read: ほらのぐち、ほらのくち
Pronunciation: 
Names and idioms with total stroke of 13:
小姫 哺む 初耳 太洸 氷斧
Names and idioms similar to 洞ノ口:
口実 呑口 艙口 贅口 人口稠密
Yojijukugo(idioms with 4 Kanji characters) including 洞ノ口:
口角飛沫 繍口錦心 嗇夫利口
Idioms including 洞ノ口:
口を開く 口に合う 糊口を凌ぐ