dimension (n.)

late 14c., dimensioun, "measurable extent, magnitude measured along a diameter," from Latin dimensionem (nominative dimensio) "a measuring," noun of action from past-participle stem of dimetri "to measure out," from dis- (see dis-) + metiri "to measure," from PIE root *me- (2) "to measure."

Sense of "bulk, size, extent, or capacity" is from 1520s, Meaning "any component of a situation" is from 1929. As a kind of realm or universe by 1912. Related: Dimensional; dimensions.

There is a fifth dimension beyond that which is known to man. It is a dimension as vast as space and as timeless as infinity. It is the middle ground between light and shadow, between science and superstition, and it lies between the pit of man's fears and the summit of his knowledge. This is the dimension of imagination. It is an area which we call The Twilight Zone. [Rod Serling, opening narration for "The Twilight Zone," 1959.]