"practicing beggary, living by alms or doles" (in reference to orders of friars), late 15c., mendicaunt, from Latin mendicantem (nominative mendicans) present participle of mendicare "to beg, ask alms," from mendicus "beggar," originally "cripple" (connection via cripples who must beg), from menda "fault, physical defect," from PIE root *mend- "physical defect, fault" (see amend (v.)).
Meaning "reduced to beggary, begging" is from 1610s. The older word in Middle English in relation to religious orders was mendinant (mid-14c.), from Old French mendinant, present participle of mendiner "to beg," from the same Latin source. The mendicant orders (freurs mendicantes or begging friars, principally the Franciscans, the Carmelites, and the Augustinians) were those religious orders which originally depended for support on the alms they received.
"a beggar, one who lives by asking alms," late 14c., from Latin mendicantem (nominative mendicans), noun use of present participle of mendicare "to beg, ask alms" (see mendicant (adj.)).