Polyglycolic acid (PGA) is a biodegradable polymer commonly used in various medical applications. It has several synonyms, including polyglycolide, polyglycolic anhydride, and poly(dl-lactic-co-glycolic acid). However, when it comes to antonyms for PGA, there are several options. For instance, non-biodegradable polymers like polystyrene, polyethylene, and polypropylene are antonyms for PGA as they do not break down easily in the environment. Furthermore, non-absorbable sutures made of nylon, silk, or polyester are also antonyms for PGA, which is commonly used as an absorbable suture material.