Metathesis

Part of speech: noun (n.)

1. Transposition, as of the letters or syllables of a word; as, pistris for pristis; meagre for meager.

2. A mere change in place of a morbid substance, without removal from the body.

3. The act, process, or result of exchange, substitution, or replacement of atoms and radicals; thus, by metathesis an acid gives up all or part of its hydrogen, takes on an equivalent amount of a metal or base, and forms a salt.