Learner's definition of CERTIFIED
1 : having met the official requirements that are needed to do particular type of work
a certified instructor
You must be certified in order to practice medicine.
The carpentry work must be done by someone who is certified for the job.
nationally certified [=(Brit) certificated] teachers
a board-certified doctor [=a doctor whose qualifications have been approved by an official group]
2 a : officially approved as having met a standard b informal : real or genuine