Answer:
The knight in the Wife of Bath's tale an antihero because he had raped a young beautiful maiden.
Explanation:
As defined in the question, an antihero is the protagonist of the play or the novel yet lacks heroic qualities and possess some of villainous qualities.
In the tale of Wife of Bath, in the Canterbury Tales of Geoffrey Chaucer, the knight is an antihero. The protagonist of the tale is a young lusty knight who rapes a young beautiful woman. And besides, he is very careless in giving promises as with the old lady, he is ungrateful towards the woman who saved his life from being punished.
A knight, in those ages, was a person of integrity and virtue, noble and courageous. But the knight picturised in the tale of Wife of Bath was opposite to what a true knight is.
To support the answer detail from the tale is listed below:
"Hadde in his hous a lusty bacheler,
That on a day cam ridynge fro ryver,
And happed that, allone as he was born,
He saugh a mayde walkynge hym biforn,
Of which mayde anon, maugree hir heed,
By verray force, he rafte hire maydenhed"