Connecting Your Condition to Impairments
There are a wide range of disabling medical conditions (physical and psychological) that serve as the basis for applying for disability benefits. Each medical condition, whether physical or psychological has "impairments" that result from the condition in question and which cause "limitations" affecting one's ability to work.
SSA utilizes the term "Impairments" (and resulting "limitations" - why you cannot work) are the essential bits of information that must be clearly and consistently documented throughout your medical history by the treating sources (medical doctors, psychologists, psychiatrists).
SSA additionally utilizes the term "Residual Functional Capacity" (RFC); this is a key concept related to the resulting physical and/or mental impairments from conditions for which the disability claim is based upon and the impact upon ability to work.
SSA has its own forms that are used for Physical RFC here and for Mental RFC here. These forms can be filled out by the treating source who has the opportunity to examine the patient and understand the limitations which result from his/her condition and thereby document with specificity in the language of SSA disability.