Urbandictionary, Martha:

(noun)a term used to describe a girl who's a genuine badass; a successful independent woman who doesn't take crap from no one and is well respected by everyone; everyone she meets loves her and just flat out envies how bad-ass she is; may be used in adj. form

ex:

The new girl applied to the new teaching program and was such a bad-ass that she got in; the interviewers were stunned by her sense of martha-ness.