The term 'expression of pain' can be expressed in two words: AH and OUCH. AH is an interjection used to express surprise, pain, or dismay. It is often used as an exclamation of surprise or pain, and is usually uttered with a short, sharp intake of breath. OUCH is an exclamation of pain, typically uttered when one has been hurt or injured. It is also used to express sympathy or empathy for someone else's pain. Both words are used to express physical or emotional pain.