Synonyms and Antonyms

A senate is a ruling body.

Raucous means harsh.

An incubus is a demon in male form who according to mythological and legendary traditions, lies upon sleepers. 

Patronise means to support.

A gust is a blast of air or wind.

Coy means someone who is reserved.

Communism means collectivism.

Erudition means learning, education and wisdom.

Skepticism means doubt.

Envy means rivalry.

'Unimportant' is antonym of 'fundamental'.

Ambiguous means having multiple possible meanings or interpretations, which creates doubt or uncertainty. 'Doubtful' correctly captures this sense - when something is ambiguous, it's unclear and therefore doubtful. Clearness, ambition, and transparent are antonyms or unrelated to ambiguous.

Admire means to praise. Condemn means to criticise.

Inanimate means 'non-living' things. Option (4) is the correct antonym.

Dispel means to eliminate. Gather means 'to collect'.

Limitation means restriction. Freedom means liberty.

Pouncing means jumping suddenly upon someone so as to attack. Option (1) does not signify jumping, so it is not the exact meaning. 

Dissuade means to convince someone not to do something. Persuade means to induce someone to do something by reason or argument.

Bewilder means to perplex or confuse. 'Enlighten' is the required antonym.

Ingenuity means cleverness. Ignorance means the state or fact of being ignorant; lack of knowledge, learning, information, etc. 

Luscious means something pleasingly tasty. 'Distasteful' is the required antonym.

Abstruse means something difficult to understand.

The opposite of 'upward motion' is downward movement. 'Descent' means the act of moving downward, which is the direct opposite. Abstruse means difficult to understand, befell is past tense of befall (happen), and porter is a person who carries things - none are opposites of upward motion.

Stagnation means a state of not moving or progressing, remaining motionless. The opposite would be movement or motion. Motionless is synonymous with stagnation, not opposite. Streamline means to improve efficiency, and perish means to die - neither are direct opposites.