Intelligible = that can be easily understood ; clear to the mind.
- When you address primary school students, use only the vocabulary intelligible to them.
- Due to some interruption in the telephone only some of his words were intelligible.
- His speech was intelligible even to the laymen.
- Intelligible speech/explanation.
Intelligent = having ,showing intelligence ; brilliant.
- Reshma is a very intelligent and hard-working girl.
- He had a few intelligent things to say on the subject.
- He writes intelligently about the current political situation.
- An intelligent boy/question.