Bereavement vs. mourning

Briana asked: What is the difference between bereavement and mourning?

The meanings of these two nouns are similar, as you can see from these two entries in Merriam-Webster's Learner's Dictionary:

mourning  noun

[noncount] 1 : the act of mourning for someone who died

• She is still in mourning for her dead husband.

• She went into mourning for dead husband [= she began mourning for her dead husband]

2 : a great sadness felt because someone has died

• a period of deep mourning

bereavement  noun, formal

1 [noncount] : being sad because a family member or friend has recently died

• a period of bereavement

2 : the death of a family member or friend [noncount]

• a period of grief after bereavement

• [count] People who have recently suffered bereavements may not be able to return to their old lives for a long time.

However, as is often true for words with similar meanings, there are differences in usage:

1. Bereavement is a more formal word and is used mostly in writing.

2. Mourning is less formal and is used in both speaking and writing.

3. Bereavement can be used as both a count noun and as a noncount noun (see the examples in the bereavement entry above).

4. Mourning can be used in a  metaphorical way, to talk about a loss related to something other than someone's  death, as in this example:

•  
  • She is mourning the loss of the quiet life she used to live, in the high snowy mountains.