HDL or high-density lipoprotein is commonly known as the "good" cholesterol because it helps remove harmful cholesterol from the bloodstream. However, finding synonyms for HDL can be difficult and even impossible as HDL is a specific molecule with a unique function in the body. Trying to find synonyms for it would be like searching for synonyms for the word "heart" or "brain." The best approach would be to use related terms that describe HDL's function, such as "cholesterol scavenger," "cardioprotective," or "anti-atherogenic." These terms help to convey the importance of HDL in maintaining overall cardiovascular health.