What is the meaning of substance dependence?

Maladaptive pattern. Substance abuse, also known as drug abuse, is a maladaptive patterned use of a substance (drug) in which the user consumes the substance in amounts or with methods not condoned by medical professionals. Substance abuse/drug abuse is not limited to mood-altering or psycho-active drugs. Activity is also considered substance abuse when inappropriately used(as in steroids for performance enhancement).