noun / verb
purpose
PER-pus/ˈpɜːrpəs/
An intended goal or reason for doing something.
She places a bucket under the leak for the purpose of catching water.

Etymology
The pieces express putting something forth: setting an action before oneself as something to be done. That proposed action or intention gives purpose its sense of the aim behind what someone does.
In context
… build on the main purpose in the introductory first paragraph and the last is final paragraph the final paragraph should shortly summarize the intent of the formal letter
More examples
- The meeting had a clear purpose.
- He purposed to finish the journey before winter.
- They questioned the purpose of the extra test.
Forms
purpose · purposes · purposed · purposing
purposeful adjective — Acting with a clear aim.