What is the meaning of Maternal_aunt?

An aunt on one's mother's side of the family, including both

  1. A sister of one's mother.
  2. A sister-in-law of one's mother; the wife or ex-wife of a maternal uncle.

A sister of one's mother.

A sister-in-law of one's mother; the wife or ex-wife of a maternal uncle.

A similar great aunt, etc.

Source: wiktionary.org