n. In grammar, transposition, more especially of the letters, sounds, or syllables of a word, as in the case of Anglo-Saxon ācsian, ās-cian, English ax, ask; Anglo-Saxon brid, English bird.n. In surgery, a change in place of a morbid substance; an operation removing a morbific agent from one part to another, as in couching for cataractn. In logic, same as conversion.