1. TremulousMeaning: quivering as from weakness or fear
Synonyms: shivering, palpitating, trembling, quavering, shaking, wobbly
Antonyms: calm, stable, unwavering, steady
2. ThrallMeaning: the state of being under the control of another person
Synonyms: captivity, subjugation, servitude
Antonyms: freedom, liberty, liberation, autonomy
3. SkulkMeaning: lie in wait or behave in a sneaky manner
Synonyms: crouch, prowl, slink, snoop, hide
Antonyms: encounter, confront.
4. RileMeaning: disturb, especially by minor irritations
Synonyms: annoy, inflame, roil, bother, irk, vex, disturb, exasperate
Antonyms: appease, placate, mollify
5. ProfuseMeaning: produced or growing in extreme abundance
Synonyms: lavish, copious, ample, bountiful
Antonyms: scant, sparse, meagre, inadequate
6. OstentatiousMeaning: intended to attract notice and impress others
Synonyms: splashy, extravagant, flamboyant, garish
Antonyms: modest, moderate, plain, tasteful
7. MotleyMeaning: consisting of a haphazard assortment of different kinds
Synonyms: eclectic, assorted, diverse, ragtag, amalgamated
Antonyms: uniform, homogenous, identical
8. LicentiousMeaning: lacking moral discipline
Synonyms: lewd, lecherous, promiscuous, salacious, unprincipled
Antonyms: chaste, controlled, innocent
9. IntersticeMeaning: small opening between things
Synonyms: interval, interruption, hiatus, interlude, pause, intermission
Antonyms: stretch, continuity, progression
10. GrappleMeaning: work hard to come to terms with or deal with something
Synonyms: confront, contend, face, clash, deal with, cope
Antonyms: make peace, surrender, agree
11. ObdurateMeaning: stubbornly persistent in wrongdoing
Synonyms: merciless, pitiless, ruthless, callous
Antonyms: benevolent, benignant, sensitive
12. PropinquityMeaning: the property of being close together
Synonyms: adjacency, contiguity, nearness
Antonyms: farness, distant
13. RecumbentMeaning: lying down or in a position of rest
Synonyms: sprawl, prostate, supine, recline
Antonyms: erect, upright
14. RecusantMeaning: someone who refuses to conform to established standards of conduct
Synonyms: rebellious, defiant, contumacious, dissident, wayward
Antonyms: compliant, amiable, docile, amenable
15. ScourgeMeaning: something causing misery or death
Synonyms: affliction, plague, bane, torment, misfortune
Antonyms: blessing, godsend
Practice these words at regular intervals, and keep an eye on this space for more such posts!