The word 'un-' is a prefix that is added to the beginning of a word to give it the opposite meaning.

She is pregnant with her first child.

Prejudice is a harmful mindset that can lead to discrimination.

I need to do some preparation before the exam.

I am prepared for the exam.

You can omit the preposition in this phrase.

My daughter attends a preschool.

I need to get a prescription for my medication.

Her presence in the room was undeniable.

In the present moment, we need to focus on what we can achieve together.