If you want the dictionary definition, just double click on any word.

Moan as a verb, means to make a complaint in an unhappy voice, usually about something which does not seem important to other people.

For example:-

The British always moan about the weather.

Mourn is a verb that means to feel or express great sadness, especially because of someone's death.

For example:

Many people in the UK mourned the death of Princess Diana.

For Xeb