poor (adj.) Look up poor at Dictionary.com
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" (see paucity) and parare "to produce, bring forth" (see pare).

Replaced Old English earm. Figuratively from early 14c. Meaning "of inferior quality" is from c.1300. Of 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.
poor (n.) Look up poor at Dictionary.com
"poor persons collectively," mid-12c., from poor (adj.). The Latin adjective pauper "poor" also was used in a noun sense "a poor man."