Definition:
“The direct opposite”
www.merriam-webster.com/dictionary/antithesis. Accessed 6 Sept. 2022.
Informal definition:
In literature, an antithesis is when two opposite ideas are presented within the same sentence and are heavily contrasting.
Examples:
It was time for joy, and it was time to mourn
It was the age of intellect, and it was the age of immaturity
She was wise, She was ignorant.
Etymology:
“from Greek antitithenai ‘set against’, from anti ‘against’ + tithenai ‘to place’.”
"Antithesis." Oxford Learner's Dictionaries, www.oxfordlearnersdictionaries.com/us/definition/english/antithesis. Accessed 6 Sept. 2022.
Rahul S