From Middle English erraunt [and other forms], from Anglo-Norman erraunt, from Old French errant, the present participle of errer (“to walk (to); to wander (to); (figuratively) to travel, voyage”), and then: * from Vulgar Latin iterāre (compare Late Latin itinerāre, itinerāri (“to travel, voyage”)), from Latin iter (“a route (including a journey, trip; a course; a path; a road)”), ultimately from Proto-Indo-European *h₁ey- (“to go”); and * from Latin errantem, the accusative feminine or masculine singular of errāns (“straying, errant; wandering”), the present active participle of errō (“to rove, wander; to get lost, go astray; to err, wander from the truth”), ultimately from Proto-Indo-European *h₁ers- (“to flow”). Doublet of arrant.
1
Straying from the proper course or standard, or outside established limits.
In that there are just seven Planets or errant Stars in the lower Orbs of heaven: but it is now demonstrable unto sense, that there are many more1650, Thomas Browne, Pseudodoxia Epidemica: […], 2nd edition, London: […] A[braham] Miller, for Edw[ard] Dod and Nath[aniel] Ekins, […], →OCLC, 6th book, page 244:
They were all doomed to be disappointed, however, for the errant engine decided at Stanley junction to spend the remainder of its crowded hour of freedom on the Aberdeen line, and finally came to rest, short of breath, in the dip between Ballathie and Cargill, near the bridge over the Tay.1941 October, “Notes and News: A Highland Runaway”, in Railway Magazine, page 469:
We ran down the street in pursuit of the errant dog.
4
Obsolete, With a negative connotation Obsolete form of arrant (“complete; downright, utter”).
Thy company, if I slept not very well / A nights, would make me an errant fool […]1611, Ben[jamin] Jonson, Catiline His Conspiracy, London: […] [William Stansby?] for Walter Burre, →OCLC, (please specify the page):
From Middle English erraunt [and other forms], from Anglo-Norman erraunt, from Old French errant, the present participle of errer (“to walk (to); to wander (to); (figuratively) to travel, voyage”), and then: * from Vulgar Latin iterāre (compare Late Latin itinerāre, itinerāri (“to travel, voyage”)), from Latin iter (“a route (including a journey, trip; a course; a path; a road)”), ultimately from Proto-Indo-European *h₁ey- (“to go”); and * from Latin errantem, the accusative feminine or masculine singular of errāns (“straying, errant; wandering”), the present active participle of errō (“to rove, wander; to get lost, go astray; to err, wander from the truth”), ultimately from Proto-Indo-European *h₁ers- (“to flow”). Doublet of arrant.