rule of three

alternative the Rule of Three · alternative the rule of threes

1. educationA rule stating that, if two ratios are equal, then the denominator of the second equals its numerator times the reciprocal of the first ratio: if a/b=c/d then d=(bc)/a.

   Multiplication is vexation, / Division is as bad; / The Rule of Three doth puzzle me, / And Practice drives me mad.

   1886, James Orchard Haliwell, The Nursery Rhymes of England, 5th edition, page 78

2. medicineA rule for clinical trials used for determining the rate of adverse side effects when no such side effects present during the course of the trial.
3. rhetoriccomedyA rule which states that things which come in groups of three are inherently funnier or more effective than things which come in groups of other sizes.
   1. rhetoriccomedySpecifically, the technique of having a setup in advance, a reminder to keep it fresh in the audience's memory, and then a payoff.
4. WiccaA religious tenet stating that the energy a person puts out into the world, positive or negative, will be returned to that person threefold.
5. computingA rule of thumb in the C++ programming language, stating that any class that defines a destructor, a copy constructor, or a copy assignment operator should define all three of them.
6. survivalA mnemonic guideline that outlines the average limits of human endurance.

alternative the Three-Fold Law · alternative the Law of Return

1. WiccaAlternative letter-case form of rule of three (sense 4); a religious tenet held by some Wiccans, stating that whatever energy, positive or negative, a person puts into the world will be returned threefold.

   Synonyms: karma, golden rule