Acquired characteristic is the originally used in genetics to describe a change that occurs in the physical structure of an organism as a result of its own activities or its interaction with the environment, i.e. a characteristic (like a bodybuilder's biceps) that is not innate.
There has long been an argument as to whether acquired characteristics can be genetically transferred to offspring. Nowadays this argument is generally considered a loser, though interest in it may still revive.
In psychology, skills acquired by learning (like reading and writing) are sometimes referred to as acquired characteristics.