The word “disability” evokes images of ramps, lower-positioned urinals, grab bars and other allowances in our architectural landscape. But an untold number of people have disabilities — from A.D.H.D. to addictive disorder to lupus — that aren’t necessarily helped by a reserved parking spot. A person who walks with a limp but uses no physical support may be jostled on the street like anyone else. An autistic person, or a person with a mental illness, will often be disdained or even assailed for peculiar or antisocial behavior.