This surname is derived from a geographical locality. 'of Ainsworth,' a chapelry in the parish of Middleton, Lancashire, formerly Aynesworth.

William de Aynesworth, Lancashire, 1332: Lay Subsidy (Rylands).

John de Aynesworth, 43 Edward III: Baines' Lancashire.

Lawrence Ainsworth, of Pleasington, 1573: Wills at Chester.

William Allen, of Ainsworth, 1588: ibid.

Cecilia Ainsworth. of Ainsworth, widow, 1630: ibid. (1620-50).

John Aynsworth (Line. Coll.): Register of the University of Oxford.

A chapelry in the parish of Middleton, near Manchester. AIR. From Ayr, a town of Scotland, capital of Ayrshire. The family had doubtless lost sight of their having been originally "of that ilk" when they assumed for arms, Argent, a cameleon proper, in allusion to the unsubstantial food of that animal.

(British and Welsh.) Local. From aim, a spring, a river, and gwerth, a place, possession, or court. In the British and Gaelic, Aun, Ain, Au, Hain, Aon, and Avon, signify a river; the place or possession on the river.

The Ainsworths, who derive their name from a Lancashire township, are at present most numerous in the Blackburn district. The Ainsworths of Plessington, an ancient family, came into the possession of the manor of Plessington in the reign of Henry VI. Another ancient family of the name lived in the vicinity of Bolton. Henry Ainsworth, the eminent biblical scholar of the 16th and 17th centuries, belonged to the Plessington family: whilst Robert Ainsworth the celebrated lexicographer of the 17th and 18th centuries hailed from the Bolton stock (B.).