bodyguard; bouncer; security guard
A person hired to protect someone or guard a place, often with a connotation of physical strength or intimidation. Can refer to a personal bodyguard, a club bouncer, or a hired guard.
The company president always has a bodyguard with him.
The bouncer at that bar looks really tough.
door bar; bolt
A physical bar or bolt used to secure a door or gate, preventing entry. This is a less common, more literal use of the word.
At night, we put the bar across the gate.
self-defense stick; pole for self-defense
Original meaning: a stick or pole carried for self-defense. Now largely historical; the modern word is almost always used for a person (sense 1).
Travelers in the old days walked with a self-defense stick in hand.
The club hired a former pro wrestler as a bodyguard.
He's the bouncer at this bar.
He has served as the president's bodyguard for many years.