To shut oneself in; to stay confined in a room or place; to seclude oneself or hide away.
風邪を引いて一週間ほど部屋にこもっていた。
I had a cold and stayed in my room for about a week.
彼は試験期間中ずっと図書室にこもって勉強した。
He shut himself in the library and studied throughout the exam period.
最近、息子が部屋にこもりがちで心配だ。
Lately my son tends to shut himself in his room, and I'm worried.
To be filled with emotion, enthusiasm, or a particular quality (e.g., 'filled with passion'). Often used as ～のこもった.
彼の演説には強い情熱がこもっていた。
His speech was full of strong passion.
この手紙には感謝の気持ちがこもっている。
This letter is imbued with gratitude.
この料理は母の愛情がこもっているようだ。
This dish seems to be made with a mother's love.
To fill a space (with smoke, smell, etc.); to be stuffy or dense with something (e.g., smoke, odor).
台所に料理のにおいがこもっている。
The kitchen is filled with the smell of cooking.
窓を閉め切ると部屋に熱気がこもって暑い。
When all the windows are shut, heat gets trapped in the room and it's hot.
煙がこもっていたので、窓を開けた。
Smoke had built up, so I opened the window.
To sound muffled — a voice or sound that is not clear, sounding as if it is coming from within something.
風邪で声がこもって、電話ではよく聞き取れなかった。
My voice was muffled from a cold, so I couldn't be heard well on the phone.
古いマイクだと音がこもって聞こえることがある。
An old microphone can sometimes make the sound seem muffled.
To hold or take refuge in a castle or fortress; to be besieged or to defend from within.
敵の侵攻を受け、兵士たちは城にこもって抵抗した。
Under enemy attack, the soldiers holed up in the castle and resisted.
To seclude oneself in a temple to pray or meditate; to confine oneself for religious practice.
事故を悔い改めるために彼は寺にこもった。
He secluded himself in a temple to repent for the accident.