The pronunciation of irrelevant [ih-rel-uh-vuh nt] /ɪˈrɛl ə vənt/ (Show IPA)
as [ih-rev-uh-luh nt] /ɪˈrɛv ə lənt/
as if spelled irrevelant,
is the result of metathesis, the transposition of two sounds, in this case, the [l] /l/
and the [v] /v/
Relevant, the base word, is occasionally subject to the same process. Analogy with words like prevalent
may play a role. A similar reordering of the [l] /l/
and [v] /v/
consonant sounds, althought not a strict one-to-one metathesis, can be heard for Calvary [kal-vuh-ree] /ˈkæl və ri/
when pronounced [kav-uh l-ree] /ˈkæv əl ri/ .
Here the transposition is reinforced by the existence of the familiar word cavalry.