11. Invulnerable (adj.)

Not able to be wounded or hurt; shielded against attack

Medieval lords did everything possible to make their castles invulnerable fortresses.

Synonyms: impregnable, impervious, immune
Antonyms: unlimited, immeasurable, everlasting, eternal

12. Malevolent (adj.)

Spiteful, showing ill will

While pretending to be a loyal friend, Iago told Othello malevolent lies.

Synonyms: malicious, wicked, sinister, malignant
Antonyms: kind, benevolent, compassionate

13. Nonchalant (adj.)

Cool and confident, unconcerned

The elegantly dressed couple strolled down the boulevard with a nonchalant air.

Synonyms: composed, unruffled, indifferent, blasé
Antonyms: perturbed, agitated, disconcerted, abashed

14. Omniscient (adj.)

Knowing everything: having unlimited awareness or understanding

Scientists today have so much specialized knowledge that they sometimes seem omniscient.

Synonyms: wise, all-knowing
Antonyms: ignorant, unknowing

15. Panacea (n.)

A remedy for all ills: cure-all: an answer to all problems

Synonyms: universal cure, easy solution

16. Scrupulous (adj.)

Exact, careful, attending thoroughly to details: having high moral standards, principled

Scientists are trained to record their observations with scrupulous accuracy.

Synonyms: painstaking, meticulous, conscientious
Antonyms: careless, negligent, remiss, dishonest

17. Skulk (v.)

To move about stealthily; to lie in hiding

The burglar skulks in the alley looking for a way to get into the darkened jewelry store without attention of anyone who might be nearby.

Synonyms: lurk, slink, prowl

18. Supercilious (adj.)

Proud and contemptuous; showing scorn because of a feeling of superiority

Their supercilious attitude toward their servants was extremely offensive.

Synonyms: snobbish, patronizing, overbearing
Antonyms: humble, meek, deferential, servile

19. Uncanny (adj.)

Strange, mysterious, weird, beyond...