'Superposition' definitions:

Definition of 'superposition'

noun

(geology) the deposition of one geological stratum on another

noun

(geology) the principle that in a series of stratified sedimentary rocks the lowest stratum is the oldest [syn: principle of superposition, superposition principle, superposition]

noun

(geometry) the placement of one object ideally in the position of another one in order to show that the two coincide

noun

The placement of one thing on top of another

From: GCIDE

Superposition \Su`per*po*si"tion\, n. [Cf. F. superposition. See Super-, and Position.] The act of superposing, or the state of being superposed; as, the superposition of rocks; the superposition of one plane figure on another, in geometry. [1913 Webster]