'Rare' is the opposite of 'frequent', meaning not occurring often.

'Pessimistic' is the antonym of 'optimistic', which refers to a negative outlook.

'Defeat' is the antonym of 'victory', indicating a loss in a competition.

'Contract' is the opposite of 'expand', meaning to decrease in size.

'Diminish' is the opposite of 'increase', which means to make smaller or reduce.

'Quiet' is the opposite of 'noisy', referring to a lack of sound.

'Complicated' is the opposite of 'simple', meaning something that is difficult to understand.

'Fail' is the opposite of 'succeed', indicating a lack of success.

'Defeat' is the opposite of 'victory', indicating loss.

'Obscure' means not visible or hard to see, which is the opposite of 'visible'.

'Descend' means to go down, which is the opposite of 'ascend'.

'Contract' means to become smaller, which is the opposite of 'expand'.

'Rare' is the antonym of 'frequent', indicating something that does not happen often.

'Selfish' is the antonym of 'generous', indicating a lack of willingness to share.

'Failure' is the opposite of 'success', indicating a lack of achievement.