c. 1200, "lacking money or resources, destitute; needy, indigent; small, scanty," from Old French povre "poor, wretched, dispossessed; inadequate; weak, thin" (Modern French pauvre), from Latin pauper "poor, not wealthy," from pre-Latin *pau-paros "producing little; getting little," a compound from the roots of paucus "little" (from PIE root *pau- (1) "few, little") and parare "to produce, bring forth" (from PIE root *pere- (1) "to produce, procure").
It replaced Old English earm (from Proto-Germanic *arma-, which is of disputed origin). Used figuratively from early 14c. Meaning "of inferior quality" is from c. 1300. In reference to inhabited places from c. 1300; of soil, etc., from late 14c. The poor boy sandwich, made of simple but filling ingredients, was invented and named in New Orleans in 1921. To poor mouth "deny one's advantages" is from 1965 (to make a poor mouth "whine" is Scottish dialect from 1822). Slang poor man's ________ "the cheaper alternative to _______," is from 1854.