(mathematics) the set of rigid motions that are also affine transformations.

(mathematics) The group of all affine transformations of a finite-dimensional vector space.

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

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

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

(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 form of polygynous, polyandrous marriage in which more than one man and more than one woman form a family unit.

(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.

(astronomy) The small cluster of galaxies that contains the Milky Way Galaxy; includes Andromeda, Triangulum, the Large Magellanic Cloud, Small Magellanic Cloud and others.