There are several synonyms for the word "mother in law". Some people say "mother-in-love" to show affection and appreciation for their spouse's mother. Other alternatives include "mom-in-law", "mum-in-law", "maternal-in-law" and "step-mother-in-law" if the person is the second spouse of the father. Some people may also refer to their mother in law as simply "mom" or "momma". Whatever term someone chooses to use, it is important to maintain a respectful and positive relationship with their mother in law as she is a crucial part of their spouse's family and potentially their own extended family.