(chiefly US) The notion that one drop of white blood (i.e. any white ancestry at all) makes a person white.

Alternative form of there is an exception to every rule

(physics) A mnemonic that uses the right hand to show the direction of induced current when a conductor moves in a magnetic field. The right hand is held with the thumb, first finger and second finger mutually perpendicular to each other; then the thumb represents the direction of motion of the conductor; the first finger represents the direction of the field; and the second finger represents the direction of the induced or generated current.

(chiefly computing) A set of rules.

plural of ruleset

(rare) Without rules.

(archaic) second-person singular simple present form of rule