The refusal or inability to accept something as true; misbelief; an instance of this.
Middle English; earliest use found in Ayenbite of Inwyt. From misbelieve + -ing.
1Holding a false belief; heretical, unorthodox.
2Not believing; sceptical; = "disbelieving [adjective]".
Middle English; earliest use found in Arthour and Merlin. From misbelieve + -ing.