The term 'From the Bottom of One's Heart' is an expression used to emphasize the sincerity of one's feelings. The crossword solutions for this term are SINCERELY (9 letters), DEEPLY (6 letters), and DEEPFELT (8 letters). SINCERELY is an adverb that means in a sincere manner, while DEEPLY is an adverb that means to a great degree or intensity. Lastly, DEEPFELT is an adjective that means having or showing strong emotion or conviction. All three words can be used to express the same sentiment of heartfelt sincerity.