Meaning: The meaning of surreptitious is something that is done in secret or that is kept quiet.
When someone behaves in a surreptitious way, they're being secretive.
Example: They were surreptitious about how they organized the surprise party.
Synonyms: Clandestine, Covert, Furtive, Unauthorized, Hidden
Antonyms: Forthright, Open, Honest, Truthful

Meaning: To bring to public notice or make known publicly
To promulgate is to officially put a law into effect.
Example: You should write an article to promulgate the benefits of eating organic food.
Synonyms: Declare, Notify, Promote, Advertise, Enact
Antonyms: Collect, Conceal, Gather, Hide, Refrain

Meaning: Vacillate means to waver back and forth, unable to decide.
To waver in mind or opinion, to oscillate or fluctuate.
Example: It seems like you vacillate between 10 and 20 members at any given time.
Synonyms: Fluctuate, Dither, Waver, Change, Stagger
Antonyms: Remain, Stay, Hold, Persist

Meaning: Corpulent is a formal word that describes a fat person.
Large or bulky of body; stout; fat
Example: When describing a fat man, you might refer to him as a "corpulent gentleman."
Synonyms: Fleshy, Obese, Portly, Burly
Antonyms: Skinny, Thin, Underweight, Slender

Meaning: 1.Agreeably pungent or sharp in taste
2. Agreeably stimulating, interesting or attractive
Example: Grandma’s home-made gravy is zesty and piquant.
Someone who's piquant engages you with charm and wit.
Synonyms: Racy, Pungent, Tangy, Interesting, Flavorful
Antonyms: Bland, Clean, Flavorless, Dull, Tasteless