in no uncertain terms
Emphatically, definitely so. For example, Jane told them in no uncertain terms that she wanted no part of their practical joke. The double negative in this idiom serves for emphasis. [Mid-1900s] Also see in so many words.
Words nearby in no uncertain terms
in memory of,
in mind,
in name only,
in no case,
in no time,
in no uncertain terms,
in nomine,
in nothing flat,
in omnia paratus,
in on, be,
in one blow