When you breath out deeply after you've been holding your breath from fear, this is an example of a time when you expel your breath.
When a school kicks out a student for cheating, this is an example of time when the school expels the student.
Expel an invader.
Expelled a sigh of relief.
Expelled the student from college for cheating.
Origin of expel
- Middle English expellen from Latin expellere ex- ex- pellere to drive pel-5 in Indo-European roots
From American Heritage Dictionary of the English Language, 5th Edition