n. The act or process of rendering dissimilar or different.n. Specifically— In philology, the change or substitution or a sound to or for another and a different sound when otherwise two similar sounds would come together or very close to each other, as in Latin alienus for aliinus, Italian pelegrino from Latin peregrinus, English number (= German nummer) from Latin numerus, etc.n. In biology, catabolism (which see): opposed to assimilation.