Nouns:
* Bodyguard: A person who protects another person from harm.
* Fireguard: A protective barrier around a fire.
* Guardrail: A railing along the edge of a road or other elevated area.
* Guardhouse: A small building used for security purposes.
* Guardsman: A soldier who is a member of a guard unit.
* Handguard: A protective covering for the hand on a weapon.
* Lifeguard: A person who is trained to rescue people from water.
* Nightguard: A device worn in the mouth to protect teeth at night.
* Sideguard: A guard on the side of a machine or other object.
* Speedguard: A device that measures and enforces speed limits.
* Vanguard: The leading part of an army or group.
* Wardrobe guard: A protective cover for clothes.
Verbs:
* Guard against: To protect oneself from something.
* Guard over: To watch over and protect something or someone.
Adjectives:
* Unguarded: Not protected or defended.
* Well-guarded: Protected by a lot of guards.
This is not an exhaustive list, but it includes some common compound words with "guard".