Adirer is a defective verb. This verb only exists in infinitive, in past participle and past gerondive.
First group verbs always end with
-er as their infinitive. Endings of first group verbs are regular.
Note : Although endings are perfectly regular, spelling changes occur in the stems of verbs in
-cer,
-ger,
-yer,
-eter,
-eler,
-é-consonne(s)-er,
-e-consonne-er, verb
envoyer and similar verbs.
Here are several examples of defectives verbs:
paître.