(geology) A type of contact twinning, typically observed in plagioclase, in which the composition surfaces are parallel to one another

present participle of twin

action of the verb to twin / giving birth to twins / the pairing of similar objects (such as towns) / (crystallography) the formation of twin crystals

biparous

(crystallography) The intergrowth of two twin crystals.

The pairing of towns or cities from geographically distinct areas, in order to foster human contact and cultural links.

plural of twinning

plural of polysynthetic twinning

plural of town twinning