Lipstick
noun, の adjective
A mouth deep red is a deep red you put on your mouth. This is lipstick.
くちべに
The readings are the kun'yomi readings of both. 口 and 紅 vocab words combined into one.
口紅をポケットに入れっぱなしにしてたみたいで、乾燥機の中で溶けちゃったのよね。
I left my lipstick in my pocket and it melted in the dryer.