CGY is an abbreviation used in the field of finance to refer to "calories per gram yield". However, if we were to look for synonyms for this term, there aren't any direct alternatives. To broaden the search, we can explore other synonyms for the words "calories" or "yield". For the former, words like energy, combustion, or heat content could be used, while "yield" can be replaced with "return" or "output". Therefore, alternative phrases for CGY could be "energy output per gram" or "heat content return per gram". It's essential to keep in mind the context in which these phrases are being used, as they might not be entirely interchangeable with CGY in all situations.