What does imprudence mean? (From Ibsen's A Doll's House)

Lacking discretion; not prudent.

NORA: Isn't it possible that he was driven to do it by necessity?
HELMER: Yes; or, as in so many cases, by imprudence. I am not so heartless as to condemn a man altogether because of a single false step of that kind.
From Henrik Ibsen's A Doll's House