As nouns the difference between eight and octaeteris
is that
eight is the digit/figure 8 or
eight can be an island in a river; an ait while
octaeteris is an octennium, a period of eight (8) years (
chiefly) in the ancient greek calendar or in reference to the short lunisolar cycle.
As a numeral eight
is (cardinal) a numerical value equal to ; the number occurring after seven and before nine.