What is the meaning of Ma'am?

Chiefly used as a form of address for a woman: contraction of madam.

A polite and formal way to address a woman.

A respectful term of address to a woman of higher rank or position.

A title for a married woman.

A female schoolteacher; a schoolmarm.

To address (a woman) as "ma'am".

Source: wiktionary.org