"person with a slim physique and an introverted, thoughtful personality," 1940, coined by American psychologist William H. Sheldon from ectoderm + -morph, from Greek morphē "form, shape; beauty, outward appearance," a word of uncertain etymology. So called for the embryonic ectoderm, which develops the nervous system. Related: Ectomorphic.
)window.location='https://www.paypal.com/cgi-bin/webscr?cmd=_donations&business=byronic106@yahoo.com&lc=US&item_name=Donation+to +Help+Keep+Etymonline+Free+and+Open&no_note=0&cn=&curency_code=USD&bn=PP-DonationsBF:btn_donateCC_LG.gif:NonHosted'){kind=link}