Generally, a son's wife, his own wife, and a married woman can be called a daughter-in-law; Wife is generally a husband's term of endearment for his wife or for an old woman.
1. Daughter-in-law
In the "Beijing popular novel, a Ghost in the West Mountain Cave", the wife said: "The old daughter-in-law has seventy five years of dogs and horses, how much youth does the professor have?" The "daughter-in-law" is the old woman's humble name for herself.
2. Wife