"BREATHE" and "BREATH"

"Breathe" means to inhale and exhale. "Breath" refers to a single inhalation or exhalation. Ex.: Remember to breathe deeply and relax. She took a deep breath before diving.

"PRINCIPAL" and "PRINCIPLE"

"Principal" refers to a person in a position of authority or the primary part of something. "Principle" means a fundamental rule or belief. Ex.: The school principal addressed the students. The principal reason for our success is teamwork. Honesty is an important principle to uphold.