心底 (xīn dǐ): Bottom of one's heart (Noun) — Meaning & Stroke Order

They decided to completely bury that painful memory deep in their hearts.

He has never confessed to anyone, only burying his feelings deep in his heart.

Walking around the old street on weekends always evokes a nostalgic sentiment in my heart.

Do you really look down on him from the bottom of your heart just because he comes from a humble background?

Although he tried to numb himself with busyness, the sorrow in his heart remained.