Bergmann's rule states that individuals of the same species tend to be larger in colder climates.

Markovnikov's rule states that in the addition of a protic acid to an alkene, the hydrogen atom adds to the carbon atom with the fewer hydrogen atoms attached, while the proton adds to the carbon atom with the more hydrogen atoms attached.

The mob rules the city with an iron fist.

The work-to-rules implemented by the employees caused a significant slowdown in productivity.

The batter rule is used to measure the thickness of the cake batter.

The batter rules are important for fair play in baseball.

There is an unwritten rule in our office that you should clean up after yourself.

There are many unspoken rules in this community.

There is an unspoken rule in our office that you should clean up after yourself.

There are many unwritten rules in this organization.