To Become Hollow
To Be Dented, To Sink, To Collapse
godan verb
This word consists of kanji with hiragana attached. Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means hollow, so the verb version is to become hollow and to sink.
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You didn't learn that reading with this kanji, so here's a mnemonic to help you:
You feel like you've started to become hollow when you have a head cold (へこ). You may be all stuffed up, but it's making you so sad that you feel hollow somehow.
失恋で凹んでいます。
I’m sinking in unrequited love.
早速新車を凹ませてしまって、凹んでいます。
I'm super sad because I made a dent on my new car already.