What was the defect of Abigail Williams in The Crucible?

By defect I suppose you are refering to a weakness in her
character that results in the problems that she faces, or a negative quality that she
possesses. It is clear that Abigail Williams is a character with a number of "defects"
in this sense, but certainly her chief defect is her propensity to lie. Let us remember
how she is introduced when she first enters the play at the bedside of Betty Parris in
Act One. She is described as being:

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...a strikingly beautiful girl, and orphan, with
an endless capacity for
dissembling.

This is clearly
her biggest defect. She is above all else an actress, and she shows her dramatic talent
in a number of separate instances, managing to convince nearly everyone that she is
sincerely repenting and revealing the names of those in league with the devil and that
she is suffering demonic attacks as a result of various indivduals and their
relationship with the devil. Abigail's biggest defect is something that she tries to use
to gain what she wants, which is John Proctor.