Antonyms

'Saturnine' describes a gloomy, melancholic temperament or demeanor. 'Good-Natured' means cheerful and friendly, making it the antonym. Gloomy, dull, and morose are all synonyms for saturnine.

'Sanctimonious' describes someone hypocritically pious or self-righteous. 'Impious' means lacking reverence or dutifulness, making it the antonym. Pietistic and pharisaical are synonyms, while piety is the quality being mocked.

Ersatz is a German loanword meaning artificial, imitation, or fake (usually as an inferior substitute). The antonym (opposite) would therefore be 'natural' or genuine. 'Artificial', 'substitute', and 'imitation' are all synonyms or related concepts, not antonyms.

Soporific means causing drowsiness or sleepiness (sedative, sleep-inducing). The antonym is therefore 'active' or 'stimulating' - something that keeps you awake rather than putting you to sleep. 'Sedative', 'sleepy', and 'narcotic' are all synonyms, not antonyms.

Ham-fisted means clumsy, awkward, or lacking skill in physical movements. Adroit means skillful, clever, or dexterous - the opposite of ham-fisted. Bungling and bumbling are synonyms (clumsy), while left-handed refers to direction.

Sulfurous literally means containing sulfur, but figuratively means harsh, bitter, or caustic (like sulfuric acid). Pleasant means agreeable and enjoyable - the direct opposite. Virulent, vitriolic, and blistering all suggest harshness or severity.

Sceptred means invested with authority or sovereignty (from 'scepter' - the ceremonial staff held by monarchs). Unauthorised means without official permission or authority - the direct opposite. Empowered, sovereignty, and ruling power all relate to having authority.

Scabrous means rough to the touch, scaly, or harsh in texture. Smooth means even and free from roughness - the direct opposite. Lepidote means covered with scales, while scurfy means rough or scaly.

Scurrilous means abusive, insulting, or offensive in language. Inoffensive means not causing offense or hurt feelings - the direct opposite. Abusive and opprobrious (abusive/shaming) are similar to scurrilous, while hatred is a related negative concept.

Antonyms are words with opposite meanings. Options A, B, C, and E are all true antonym pairs: impassive (emotionless) vs ardent (passionate), phlegmatic (calm) vs zealous (fervent), vehement (furious) vs listless (lethargic), and fervid (intense) vs apathetic (uninterested). However, 'lukewarm' and 'indifferent' are NOT opposites - both suggest a lack of enthusiasm or passion. They're similar in meaning, making this the non-antonymous pair.

Inscrutable means difficult to understand or interpret, not easily deciphered. Lucid means clear, comprehensible, and easy to understand, making it the direct antonym. Abstruse and esoteric both mean difficult to understand (synonyms, not antonyms), and incomprehensible means not able to be understood (also a synonym).

Rancour means bitterness, resentfulness, or ill will toward someone. Friendliness (option A) is the direct opposite as it conveys warmth, goodwill, and pleasant demeanor rather than hostility or lingering resentment. Bitterness (option B) is actually a synonym, not an antonym.

'Fast' is indeed a contronym (self-antonym) because it has opposite meanings: 1) moving quickly (rapid, swift) and 2) fixed or immovable (stuck, fastened, hold fast). The other options don't have this contradictory property: 'fats' is just a plural noun, 'stop' means only to cease movement, and 'post' can mean to mail or a pole but these aren't true opposites. The example 'overlook' works similarly: to oversee/watch over vs. to fail to notice.

Amalgamate means combine or unite to form one organization or structure. So the best option here is split. Separate on the other hand, although a close synonym, it is too general to be the best antonym in the given question while Merge is the synonym; Collect is not related.

Periodicity is almost similar to frequency. Gradualness means something happening with time. Persistency is endurance. Rarity is opposite to frequency.