Category 1
To get or come into possession of something
Obtain
To watch something carefully
Observe
Something that blocks your way
Obstacle
Easy to see or understand
Obvious
A strong feeling of not liking something
Objection
To block or make it hard for something to move forward
Obstruct
Something that stands out in a way that is annoying or too noticeable
Obtrusive
Not influenced by personal feelings; based on facts
Objective
Hard to see or understand clearly
Obscure