antiprism

noun

an·​ti·​prism ¦an-ˌtī-¦pri-zəm 

¦an-tē-

plural antiprisms

: a polyhedron having two faces that are identical polygons in parallel planes but rotated from each other while the other faces are a series of alternately oriented triangles

These are the first clusters composed of centered square antiprisms of metal atoms.

—Francis J. DiSalvo, Science, 9 Feb. 1990

antiprismatic

¦an-ˌtī-priz-¦ma-tik 

¦an-tē-

adjective

The ytterbium environment, in keeping with the diminished ionic radius, is now eight-coordinate with a square-antiprismatic arrangement.

—Glen B. Deacon et al., Canadian Journal Of Chemistry, 1 Jan. 2009

Word History

Etymology

anti- entry 1 + prism

First Known Use

1969, in the meaning defined above

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