/euh pis"keuh tis'teuhr, ep'i skeuh tis"teuhr/ , n.
a disk with a sector removed that when rotated in front of a light source allows the periodic passage of flashes of light: used in studying the motion of a body.
Also, episkotister .
[ 1900-05; episkot ( ízein ) to overshadow (see EPI-, SCOTIA, -IZE) + -IST + -ER 1 ]