1690s, "causing dyspepsia" (a sense now obsolete); by 1789 as "pertaining to dyspepsia;" by 1822 as "suffering from dyspepsia;" from Greek dyspeptos "hard to digest," from dys- "bad, difficult" (see dys-) + peptos "digested," from peptein "to digest" (from PIE root *pekw- "to cook, ripen"). Also "characteristic of one suffering from dyspepsia" (depressed, pessimistic, misanthropic), by 1894; dyspepsical in this sense is by 1825.
