1 [count] : a device that is used to find direction by means of a needle that always points north
He always carries a compass when he walks in the woods.
Guests arrived from all points of the compass. [=directions]
2 [count] : something that helps a person make choices about what is right, effective, etc.
His religion is the compass that guides him.
Interest rates serve as a compass for determining whether to buy or sell stocks.
The character in the movie had no moral compass to tell him that stealing was wrong.
3 a [count] : a tool that consists of two pointed sticks joined at the top and that is used for measuring distances — often plural
a pair of compasses [=dividers]
3 b [count] : a tool that consists of a pen or pencil attached to a pointed stick and that is used for drawing circles
4 [noncount] : a specialized area of knowledge, skill, experience, etc. — often used after beyond or within
That topic falls beyond the compass [=beyond the scope] of my research.