The practice of having sex with multiple partners at the same time.

(physics) the propagation velocity of the envelope of a modulated travelling wave, which is considered as the propagation velocity of information or energy contained in it.

A group of people who identify with one another, especially on the basis of ancestral, national, cultural, historical or religious grounds.

(chemistry) the vertical group of the periodic table containing carbon, silicon, germanium, tin and lead; the elements have a valence of 4, and show the typical gradation from nonmetal to metal

(crystallography, mineralogy) The set of all symmetry operations that can be applied to a given crystal without changing it.

(mathematics) A group of isometries leaving a fixed point.

(chemistry) a vertical series of elements in the periodic table that have three valence electrons; boron is a metalloid, while aluminium, gallium, indium and thallium are metals

A group of people, sampled from a larger population, interviewed in open session for market research or political analysis.

A collection of humans or animals who share certain characteristics, interact with one another, accept expectations and obligations as members of the group, and share a common identity.

A group of members of a political party or of a similar organisation who have decided to create their own organisation.