WordWeb Online

1. Having only one part or element
   "a simplex word has no affixes and is not part of a compound--like 'boy' compared with 'boyish' or 'house' compared with 'houseboat'"
    
2. (telecommunication) allowing communication in only one direction at a time, or in telegraphy allowing only one message over a line at a time
   "simplex system"

1. (linguistics) a simple non-compound word
    
2. (mathematics) a figure with the minimal number of possible vertices (in given number of dimensions); an analogue in any dimension of the triangle (in 2D) or tetrahedron (in 3D)

Derived forms: simplexes, simplices

See also: simple, unidirectional

Encyclopedia: Simplex