In writing about Harvard Medical School faculty member Dr. Angelo Volandes and the films Volandes is making to help terminally-ill patients decide to opt out of medical intervention, The Atlantic contributing editor Jonathan Rauch describes Volandes' physical appearance:
Volandes, a thickening mesomorph with straight brown hair that is graying at his temples, is wearing a T-shirt and shorts and looks like he belongs at a football game.
Mesomorph means "a person with a well-developed muscular body," and in this context, Rauch uses the word to refer to Volandes' physique. However, the word's coiner, American psychologist and physician William Sheldon, meant it to describe both physique and personality. A mesomorph, according to Sheldon, was active, outgoing, lacking in inhibitions, and prone to criminal behavior.
Mesomorph was one of three physical-psychological types Sheldon described in his 1940 book The Varieties of Human Physique and created names for by combining prefixes ecto- ("outer"), meso- ("middle"), and endo- ("inner)" with the Greek -morph, meaning "shape." (Morph was ported into English as a verb meaning "to change shape.") From the Encyclopedia Britannica:
[Sheldon] classified people according to three body types: endomorphs, who are rounded and soft, were said to have a tendency toward a “viscerotonic” personality (i.e., relaxed, comfortable, extroverted); mesomorphs, who are square and muscular, were said to have a tendency toward a “somotonic” personality (i.e., active, dynamic, assertive, aggressive); and ectomorphs, who are thin and fine-boned, were said to have a tendency toward a “cerebrotonic” personality (i.e., introverted, thoughtful, inhibited, sensitive). He later used this classification system to explain delinquent behaviour, finding that delinquents were likely to be high in mesomorphy and low in ectomorphy and arguing that mesomorphy’s associated temperaments (active and aggressive but lacking sensitivity and inhibition) tended to cause delinquency and criminal behaviour.
Sheldon died in 1977 and his theories have been largely discredited. Nevertheless, mesomorph remains.