twinning

1. The bearing of twins.
2. A pairing or union of two similar or identical objects.
3. Mineralogy. The formation of twin crystals.

A process in which two or more crystals, or parts of crystals, assume orientations such that one may be brought to coincidence with the other by reflection across a plane or by rotation about an axis. Crystal twins represent a particularly symmetric kind of grain boundary; however, the energy of the twin boundary is much lower than that of the general grain boundary because some of the atoms in the twin interface are in the correct positions relative to each other.

1. the production of symmetrical structures or parts by division.
2. the simultaneous intrauterine production of two or more embryos. Twinning is a desirable feature in animals that depend for their profitability on the production of young, e.g. lambs of the meat-producing breeds, and selection for the characteristic is a standard husbandry strategy. In animals that are essentially uniparous, e.g. mares, twins represent a danger to the foals and to the mare. Twins in which one is a female and one a male have the added risk of the female being a freemartin.

Look up twinning in Wiktionary, the free dictionary.

Twinning (making a twin of) may refer to:

• In biology and agriculture, producing two offspring (i.e., twins) at a time, or having a tendency to do so;
• Town twinning
• Twinning institutional building tool
• eTwinning, a collaboration in which two schools in different locations are paired and communicate using the internet
• Widening of a road by constructing another one next to it
• In crystallography, crystal twinning refers to intergrown crystal forms that display a twin boundary
• In film, special effects that multiply the presence of the same actor or actress on screen
• In animation, twinning refers to when two parts on opposite sides of a character's body move the same way
• A type of transnational education in which a student does part of their degree course in a local private college and part of it in an overseas institution tied to the college

This disambiguation page lists articles associated with the same title. If an internal link led you here, you may wish to change the link to point directly to the intended article.

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)