Metathesis
Metathesis is the reversal of linear order of segments.
In other words, it is when children switch the order of sounds or syllables in a word when they are learning to speak.
Examples are shown below.
'ask' /æsk/ -> 'aks' [æks]
'cup' /kʌp/ -> 'puc' [pʌk]
'animal' /ænəməl/ ->
'aminal' [æmənəl]