Antonyms

Fortuitous means by chance. So, its opposite is planned.

Vindictive means being revengeful in nature. So, its opposite is forgiving.

Comfort

Small

Graceful

Virility

Frequent

Cheerful

'Querulous' means complaining, fretful, or inclined to finding fault. The opposite would be someone who is satisfied and content. 'Contented' is the correct antonym as it means satisfied and happy. 'Unhappy', 'discontented', and 'angry' are synonyms or related to querulous, not opposites. 'Gloomy' means sad, which is also not the opposite.

'Quaint' means attractively old-fashioned, unusual, or peculiar in an interesting way. The opposite would be something common, standard, or lacking special character. 'Ordinary' is the correct antonym as it means normal or usual. 'Peculiar', 'curious', and 'strange' are actually synonyms of quaint. 'Silly' means foolish, which is not the opposite.

Questionable means doubtful, open to doubt, or not reliable. Its opposite is certain, which means sure, definite, or beyond doubt. Dubious is a synonym, not an antonym.

Queer means strange or odd. Something that is not queer is often ordinary.

Quit can mean to leave, abandon, or stop doing something. Its opposite is start, which means to begin or initiate. Withdraw and abandon are synonyms of quit, not opposites.

Quiet means making little or no noise. Its direct opposite is noisy, which means making a lot of sound or disturbance. Motionless refers to lack of movement, not sound.

Quixotic means idealistic, romantic, or impractical (after Don Quixote). Its opposite is practical, which means realistic, sensible, and grounded in reality. Fantastic and romantic are actually related concepts, not opposites.