When it comes to referring to your spouse's grandmother, you may be wondering what the proper term is. While there's no specific word for grandmother-in-law, there are a few synonyms you could use. For instance, you could refer to her as your "spouse's grandmother," "grandma-in-law," "grandparent-in-law," or simply "grandma." Some other options might include "paternal/maternal grandmother-in-law" or using her first name (if you're comfortable doing so). Ultimately, it's up to you and your spouse to decide what feels most comfortable for you both. Regardless of what you call her, it's important to treat her with the same love, respect, and kindness you would any other family member.