A rule stating that an airplane designed with the same cross-sectional area distribution in the longitudinal direction as the Sears-Haack body generates the same wave drag as this body, largely independent of the actual shape; used in aerodynamics to reduce drag, typically by narrowing the fuselage at the wing roots.

(informal) Australian rules football.

plural of rule of thumb

(law) The unofficial acceptance of the use of one's spouse's private documents in court during a divorce.

(thermodynamics) An empirical rule stating that a linear relationship exists between the temperatures at which two solutions exert the same vapor pressure.

(statistics, singular only) Synonym of the 68-95-99.7 rule

plural of selection rule

plural of blood rule

(religion, Wicca) A religious tenet held by some Wiccans, stating that whatever energy, positive or negative, a person puts into the world will be returned threefold.

(Internet slang, fandom slang, informal) The proposition that there are pornographic depictions of anything and everything, especially as fan art on the Internet.