1.  tessellation(n = noun.act) - the careful juxtaposition of shapes in a pattern; "a tessellation of hexagons"
is a kind of apposition, collocation, juxtaposition

2.  tessellation(n = noun.act) - the act of adorning with mosaic;
is a kind of decoration
Derived form verb tessellate₂

   The act of tessellating; also, the mosaic work so formed. J. Forsyth. [1913 Webster]

tessellation, n.
1 the act or an instance of tessellating; the state of being tessellated.
2 an arrangement of polygons without gaps or overlapping, esp. in a repeated pattern.