心底
1
bottom of one's heart;depths of one's mind;innermost thoughts;real intentions
彼は心底は善人だ。
He is a good man at heart.
2
only applies to
しんそこ
from the bottom of one's heart;wholeheartedly;truly;sincerely
君には心底失望したよ。
I'm very disappointed in you.
Other forms
真底 【しんそこ】 (rarely used kanji form)