Etymology: < post-classical Latin ambulatorium place for walking, covered walk (in an undated glossary; from 13th cent. in British sources) < classical Latin ambulāt- , past participial stem of ambulāre ambulate v. + -ōrium -ory suffix¹.Compare Middle French, French †ambulatoire entrance hall, corridor (1535). The α. forms show various processes of reduction of the two medial syllables. Compare post-classical Latin ameltorium (1483–4 in a British source, in the anthology cited in quot. 1500-1).

Etymology: < (i) Middle French, French ambulatoire moving from place to place, itinerant (1497, originally with reference to a parliament; compare quot. 1604 at sense 1), changeable (1502, originally in a legal context in la volonté de l'homme est ambulatoire jusqu'à la mort ‘a person is free to change his or her last will as long as he or she lives’, later also in extended use), and its etymon (ii) classical Latin ambulātōrius that can be moved about, movable, suitable for walking, (in legal use) liable to change, in scientific Latin also (of a fever) ambulant (1825, in typhus ambulatorius , or earlier) < ambulāt- , past participial stem of ambulāre ambulate v. + -ōrius -ory suffix². Compare earlier ambulatory n. and later ambulant adj.Specific senses. The senses ‘adapted for walking’ and ‘of or relating to walking’ (see sense 3), are not paralleled in French until later: respectively c1808 (in patte ambulatoire ) and 1845. In senses 4b and 4c after German ambulatorisch designating facilities that provide treatment for outpatients (1804 or earlier), (of an attack of a disease) not so severe as to confine a person to bed (1863 in the passage translated in quot. 1864; late 18th cent. in the sense ‘itinerant’).