The particularity of the verb to say is to have an irregular form in the present tense of the indicative: "vous dites". This form is completely irregular and you have to learn it by heart to remember it.
- je dis
- tu dis
- il dit
- nous disons
- vous dites
- ils disent
Vous dîtes (WITH a circumflex accent) exists but it is the simple past.
Vous dites (WITHOUT a circumflex accent) is the indicative present.
Other forms of verb "dire" are completely regular:
- Imperfect : vous disiez
- Subjunctive : que vous disiez
- Future : vous direz
- Conditional : vous diriez
Derived verbs from "dire" are regular except:
- "redire" (to say again) who is conjugated on "dire" model
- "maudire" (to curse) who is conjugated on "finir" model
- interdire ==> vous interdisez
- prédire ==> vous prédisez
- médire ==> vous médiez
- redire ==> vous redites
- maudire ==> vous maudissez