"Heatingly" is an uncommon word that means "in a way that produces heat or warmth." There are several synonyms that one can use to express this same idea. One option is "thermally," which pertains to heat or temperature. Another synonym is "heatedly," which describes an argument or discussion that is intense or passionate. "Warmly" can also convey a sense of producing heat or comfort, as can "fervently," which denotes an enthusiastic or earnest manner. Additionally, "radiantly" might be used to describe something that emits warmth or heat, such as a fire or the sun. All of these words offer alternatives to "heatingly" that can help add variety and nuance to one's writing.