Gerontic is a term that is used to refer to the elderly population, particularly in the context of healthcare and medical issues. However, there are several other synonyms for the word gerontic that you can use in your writing to add variety and creativity to your work. Some of these synonyms include senior, elderly, aged, advanced in years, old, and senior citizen. Other terms that can be used include mature, seasoned, venerable, and elderly person. These synonyms can help you to avoid repetition and add depth to your writing when discussing issues related to the aging population.