\Co*lum"*nar\, a. [L. columnaris, fr. columna.]
Formed in columns; having the form of a column or columns;
like the shaft of a column.
{Columnar epithelium} (Anat.), epithelium in which the cells
   are prismatic in form, and set upright on the surface they
   cover.
{Columnar structure} (Geol.), a structure consisting of more
   or less regular columns, usually six-sided, but sometimes
   with eight or more sides. The columns are often fractured
   transversely, with a cup joint, showing a concave surface
   above. This structure is characteristic of certain igneous
   rocks, as basalt, and is due to contraction in cooling.