down
1.
to make sth fall down, open, etc. by hitting it hard :
Firefighters had to break the door down to reach the people trapped inside.
2.
to destroy sth or make it disappear, especially a particular feeling or attitude that sb has :
to break down resistance / opposition
to break down sb's reserve / shyness
Attempts must be made to break down the barriers of fear and hostility which divide the two communities.
3.
to divide sth into parts in order to analyse it or make it easier to do :
Break your expenditure down into bills, food and other.
Each lesson is broken down into several units.
—related noun breakdown
4.
to make a substance separate into parts or change into a different form in a chemical process :
Sugar and starch are broken down in the stomach.