A rule stating that the use of prior probabilities of 0 or 1 should be avoided, except when applied to statements that are logically true or false, so as to leave room for the possibility that something very unlikely is in fact the case.

The rule of a monarch characterized by a lack of consultation with the parliamentary body of the state.

Third-person singular simple present indicative form of rule OK

simple past tense and past participle of rule OK

(evolutionary biology) The principle of biology that states that populations isolated onto islands may undergo evolution towards dwarfism or gigantism to better conform to available resources

(poker) The rule of multiplying the number of outs by four to discover one's approximate chance to make one's hand on the turn or river. Compare rule of two.

(poker) The rule of multiplying the number of outs by two to discover one's approximate chance to make one's hand on the river.

(cellular automata) A simple cellular automaton, unusual in being Turing-complete, where each cell's value changes depending on its current value and those of two neighbouring cells.

(mathematics) A formula used to find the derivatives of products of two or more functions: (f·g)'=f'·g+f·g',!

(very rare) plural of Cramer's rule