apothem

Noun

ap=o=them

CIDE DICTIONARY

apothem, n. [Gr. + that which is placed, to place.].

The perpendicular from the center to one of the sides of a regular polygon. [1913 Webster]
A deposit formed in a liquid extract of a vegetable substance by exposure to the air. [1913 Webster]

apothem, n. Geom. a line from the centre of a regular polygon at right angles to any of its sides.

Etymology

Gk apotithemi put aside (as APO-, tithemi place)