distinct
Clearly different and easy to tell apart from others.
Distinct means clearly different and separate from something else, easy to tell apart. When you hear three distinct knocks on the door, you can count each knock separately because they're clear and separate. When a teacher asks for three distinct reasons, she wants three truly different ideas, not the same point restated three ways.
Something distinct stands out in a way that makes it unmistakable. A zebra's stripes create a distinct pattern you'd recognize anywhere. Your best friend might have a distinct laugh that you can identify across a crowded cafeteria. Each of the fifty states has its own distinct culture and character, making Florida feel clearly different from Montana or Maine.
The word can also describe something particularly noticeable or definite. Saying there's a distinct possibility of rain means rain seems quite likely. A distinct improvement means you can clearly see that something got better. If your teacher says she notices a distinct change in your effort, she means the difference is obvious and real, not something she has to squint to see.
The opposite of distinct is vague, blurry, or indistinct: hard to make out or tell apart.