Definition – An opponent or enemy
Sentence – The red troupe was spying on the adversary's team to find out secret information, for the red team to use against them.
Synonyms – antagonist, rival, competitor, foe, attacker
Antonyms – ally, friend, helper, supporter

Definition – self-confident in a difficult situation
Synonyms – nonchalant, selfassurance, poise
Sentence – Military soldiers entered the task force with tremendous aplomb not even knowing what lay ahead and the danger involved.
Antonyms – fear, anxiety, suspicion

Definition – anxious or fearful; uneasy
Sentence
– Some of the soldiers in the Military Air Force were feeling apprehensive when entering the air planes because they were afraid of crashing.
Synonyms – suspicious, uncertain, jittery, afraid, agitated,
Antonyms – calm, confident, certain, oblivious, unmindful

Definition – A sweet or pleasant odor ; scent
Sentence – When entering the mall I caught a whiff of a delightful fragrance that seemed to emanate from one of the aisles.
Synonyms – aroma, perfume, aura, incense
Antonyms – odor, stench, stink

Definition – sneaky; acting in a way so as not to be noticed
Sentence – The furtive cat was creeping up on the fish tank to grab hold of the fish without being caught.
Synonyms – surreptitious, hidden, sly, secretive, stealthy
Antonyms – honest, open, forthright, straightforward

Definition – physically or mentally exhausting; very hard to do
Sentence – Sometimes I hesitate when eating broccoli because it’s a very grueling task to do; I abhor that vegetable.
Synonyms – excruciating, exhausting, tortuous, challenging, difficult
Antonyms – effortless, undemanding, easy, facile

Definition – ability to grow, develop or improve; possibility
Sentence – The new cereal company has great potential of developing the best cereal in the world.
Synonyms –likely, chance, prospect, probable
Antonyms – impossible, lacking, unlikely, unpromising

Definition – very steep overhanging rock; edge of a cliff
Sentence – The Roadrunner stopped at the precipice of the cliff to avoid falling off.
Synonyms – crag, bluff, escarpment, scarp
Antonyms – incline, rise, altitude

Definition – in a pure or unspoiled state; untouched
Sentence – A young gentleman exited out of the shop with his new, pristine t shirt that he just bought.
Synonyms –flawless, perfect, spotless, fresh, immaculate, impeccable
Antonyms – affected, dirty, spoiled, stale, used

Definition – An unusual or unexpected sight
Sentence – When I was walking through the cemetery, I noticed an apparition what looked like a ghost.
Synonyms – delusion, hallucination, illusion
Antonyms – truth, reality, actuality, certainty

Definition – secret; mysterious
Sentence – I wondered about the destination that the cryptic map would lead me to that no one knew about.
Synonyms – unknown, furtive, private, ambiguous
Antonyms – straightforward, apparent, visible , obvious

Definition – exaggeratedly mournful
Sentences – One of the songs on the radio was so lugubrious that I almost broke into tears after hearing it.
Synonyms – tearful, aggrieved, grieved, dispiriting
Antonyms – cheerful, joyful, spiriting, merry, blissful

Definition – A powerful whirlpool; turmoil
Sentence – The ship was dragged into a maelstrom and pulled underneath the waves.
Synonyms – undercurrent, vortex, stir, eddy, whirl
Antonyms – calm, peace, relaxed, soothing

Definition – A large, elaborate tomb
Sentence – The grave robbers got lost in the complicated, corridors of the fancy mausoleum while trying to steal thousands of dollars worth of jewelry.
Synonyms – chamber, vault, grave, burial, sepulture
Antonyms – I couldn't find any