The phrase "chill to the bone" refers to a feeling of extreme coldness that penetrates deeply into one's body. Antonyms for this expression include words like warm, cozy, comfortable, and pleasant. Instead of feeling chilled to the bone, you might feel snug and comfortable in front of a roaring fire, or warm and toasty under a pile of blankets. Other antonyms could include adjectives like mild, tepid, lukewarm, or moderate. These words suggest a lack of extreme coldness or discomfort, and instead imply a sense of comfort and ease.