trihedron
noun
the figure determined by three planes meeting in a point.
trihedrons
-
pluralof trihedron.plural
The grammatical form denoting more than one person, place, thing, or idea.
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
So trihedrons, tetrahedrons, pentahedrons, &c., though some say, these last may end in dra, which I think improper.
From The Grammar of English Grammars by Goold Brown
