metathesis (n.)

A term used in LINGUISTICS to refer to an alteration in the normal SEQUENCE of ELEMENTS in a SENTENCE – usually of sounds, but sometimes of SYLLABLES, WORDS, or other UNITS. Metatheses are well recognized in HISTORICAL LINGUISTICS (e.g. Old English brid becoming bird), but they can also be seen in PERFORMANCE ERRORS – in such TONGUE-SLIPS as aks for ask, or in the phenomenon of ‘spoonerisms’ (cf. the dear old queen becoming the queer old dean).