expression, ichidan verb
keep to oneself; keep secret; keep inside
Used when someone keeps a thought, feeling, or secret inside without revealing it to others. Often implies a deliberate decision to not share.
彼はその秘密を胸に納めて、誰にも話さなかった。
He kept the secret to himself and told no one.
感謝の気持ちを胸に納めて、静かに会場を後にした。
I kept my gratitude inside and quietly left the venue.