Source : Free On-Line Dictionary of Computing

projective plane
     
         The space of {equivalence classes} of {vectors}
        under non-zero {scalar} multiplication.  Elements are sets of
        the form
     
        	{kv: k != 0, k scalar, v != O, v a vector}
     
        where O is the origin.  v is a representative member of this
        equivalence class.
     
        The projective plane of a {vector space} is the collection of
        its 1-dimensional {subspaces}.  The properties of the vector
        space induce a {topology} and notions of {smoothness} on the
        projective plane.
     
        A projective plane is in no meaningful sense a plane and would
        therefore be (but isn't) better described as a "projective
        space".
     
        (1996-09-28)