ambulation n.

"to move easily and gently without hard shocks," as a horse does when it first lifts the two legs on one side and then the two on the other, early 14c., from Old French ambler, in reference to a horse or other quadruped, "go at a steady, easy pace" (12c.), from Latin ambulare "to walk, to go about, take a walk," perhaps a compound of ambi- "around" (from PIE root *ambhi- "around") and -ulare, from a Proto-Italic *ala- "to wander," from PIE root *el- "to go" (source also of Greek ale "wandering," alaomai "wander about;" Latvian aluot "go around or astray"), as per de Vaan. Until 1590s used only of horses or persons on horseback. Related: Ambled; ambling.

also *mbhi-, Proto-Indo-European root meaning "around;" probably derived from *ant-bhi "from both sides," from root *ant- "front, forehead."

It forms all or part of: abaft; about; alley (n.1) "open passage between buildings;" ambagious; ambassador; ambi-; ambidexterity; ambidextrous; ambience; ambient; ambiguous; ambit; ambition; ambitious; amble; ambulance; ambulant; ambulate; ambulation; ambulatory; amphi-; amphibian; Amphictyonic; amphisbaena; Amphiscians; amphitheater; amphora; amputate; amputation; ancillary; andante; anfractuous; be-; begin; beleaguer; between; bivouac; but; by; circumambulate; embassy; ember-days; funambulist; ombudsman; perambulate; perambulation; preamble; somnambulate; somnambulism; umlaut.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit abhitah "on both sides," abhi "toward, to;" Avestan aibi; Greek amphi "round about;" Latin ambi- "around, round about;" Gaulish ambi-, Old Irish imb- "round about, about;" Old Church Slavonic oba; Lithuanian abu "both;" Old English ymbe, German um "around."