The word "freeheartedly" refers to doing something with sincerity, generosity, and with an unreserved spirit. However, antonyms for the word would be anything that describes the opposite traits. Some examples of antonyms are insincerely, reluctantly, hesitantly, half-heartedly, coldly or begrudgingly. When someone does something insincerely, they do it without genuine care or interest. Reluctantly is when someone does something with resistance or unwillingness to do it. Hesitantly means to do something with uncertainty. Half-heartedly shows a lack of enthusiasm. Doing anything coldly means to do it in a detached or distant way. Lastly, begrudgingly is doing something with resentment or displeasure.