expression, noun
bottom of one's heart; deepest feelings
Refers to one's innermost, truest feelings or thoughts. Often used in expressions like 心の底から (from the bottom of one's heart).
心の底から感謝しています。
I am grateful from the bottom of my heart.
彼は心の底では優しい人だ。
Deep down, he is a kind person.
Compound of 心 (heart, mind) + の (possessive particle) + 底 (bottom). Literally 'the bottom of the heart/mind', used metaphorically for one's deepest, truest feelings.