Découdre is a french third group verb. So, this verb is irregular and do not follow a regular conjugation pattern like first or second group verbs. Follow this link to see all the endings of the conjugation of most of the third group verbs :
conjugation rules and endings for the second group verbs.
Découdre verb is conjugated in female form and in reflexive form. Be careful, the past participle of compound tenses must agree with the subject.
Découdre verb is conjugated in interrogative form. For sound reasons, an euphonious
« t » is added to the pronoun of the third person:
« il »,
« elle »,
« on »,
« ils »,
« elles » except when the verb ends with
« t » or
« d »:
« découdra-t-elle ">« aura-t-elle décousu ? ».
Finally, the interrogative form does not exist in subjunctive and imperative.