A word used to describe someone who is either too afraid or too stubborn to develop a likable personality/identity. "Likable" in this case denotes a healthy amount of self-respect and a willingness to get along with any and everybody. The hallmark of the purebred "lame" person is a fear of personal growth and/or a fear of attaining personal traits that can be expressed openly with confidence and without excessive egoism. In various cases, lameness can be attained and cured, or pervasive and life threatening, depending on the degree of obliviousness the lame person possesses.
Person A: "What's up with Jeff? Why's he trying to imitate people?"