もったいない
もったいない · mottainai · JLPT N3 · i-adj
wasteful
🍚 mottai (勿体, a thing's true worth) + nai (not): its worth is being lost
Mottai (勿体) once meant the dignity or proper weight of a thing; nai negates it. You say mottainai when something's value goes to waste, like uneaten rice or an unused gift, or when kindness feels like more than you deserve.