In Jonson's The Alchemist, what is the relevance of the character of Dame Pliant?

Dame Pliant

Often called "Widow" in the play, she is the recently-widowed sister of Kastrill. Dame Pliant's name means bendy, supple, or flexible; true to her name, she seems one of the stupidest characters in literature. When she does speak, very rarely, she has the same speech mannerisms (e.g., "suster") as her brother. Subtle steals several kisses from her (4.2) while she seems not to notice, and the two conmen fight over which of them will wed her (and inherit the considerable fortune she has inherited from her husband). In the end, it is Lovewit who gets the girl with no wits.

Thank you for your reply. However I'm more interested with her importance within the play. What purpose is her character for, what does she represent for example?

Here is an interesting look at how women are seen in the play;

What was the position of women in Elizabethan and Jacobean England?

Doll Common and Dame Pliant are the two women in the play; they are largely in the background and do not make decisions that change the action. The Alchemist conveys the misogynist attitude common in Renaissance literature. It can be somewhat shocking to a modern audience to hear the blatant belittling of women, as Surly says to Dame Pliant: “For you’re a handsome woman: would yo’ were wise, too” (4.6, line 7). Women were considered naturally deficient in the godlike faculty of reason; therefore, they were treated as ignorant children who had to be ruled. Kestrel’s behavior to his sister is abusive by today’s standards. He threatens her with violence if she will not do as he says. She does not want to marry someone she thinks is a Spanish count but is bullied into it. Pliant is beautiful, dumb, and rich, a perfect woman in the eyes of the men who treat her as a commodity to be traded behind her back as though it is none of her business who marries her. She is the butt of crude jokes, especially between Face and Subtle. Face does not mind pimping her to the Spanish count and then having used goods. Subtle balks at this and decides to sell his share in Dame Pliant! Even Doll Common is disgusted with Pliant, calling her a “good dull innocent” (5.4, line 69).

Women were not educated as men were. In the Protestant tradition, women were taught to read so they could read the Bible, but they did not generally go to school. Doll, on the other hand, has a brain and knows enough to spout some fake theology (4.5, lines 25-32) or fairy lore or alchemy on cue. In the Renaissance, as in classical Greece and Rome, prostitutes could often be high-class call girls, afforded more education than respectable women. Doll is not aristocratic but can play the part of a lady, enough to fool Mammon. Yet, though she speaks of the equality of the “venture tripartite” (1.1, line 135), she is not an equal partner with Face and Subtle. She does what they bid her, and every night, they draw straws for her. Though good natured and the peacemaker of the group, she is given no real respect or credit for her part.

Queen Elizabeth I represents the new tradition for women of the upper class who were sometimes allowed a humanist education. In Elizabeth’s case, she was educated as a possible successor to the throne. Elizabeth had studied the classics and wrote poetry. She could hold her own intellectually with the members of court. The literature of the age was addressed to Elizabeth as the intellectual and moral inspiration for the English Renaissance. Jonson honors such a lady patroness in Mary, Lady Wroth, the educated niece of Sir Phillip Sidney, to whom he dedicates the play.