Etymology: Old English ceaster < *c^eæster < *cæster < prehistoric Old English *cæstra (5–6th cent.) feminine, < Latin castra plural neuter, ‘camp’, often applied to places in Britain which had been originally Roman encampments. (For the phonology, compare Sievers Ags. Gram. 1886, §75. 1.) This is one of the best ascertained of the Latin words adopted by the Angles and Saxons during the conquest of Britain. Still existing as the proper name, or part of the name, of many places. In Cumbria, Lancashire, Yorkshire, and some counties south of these, it appears as -caster, without palatalization. The history of the form written -cester, of which only -ster is pronounced (in Worcester, Bicester, etc.), is obscure; the written form is perhaps of French or medieval Latin origin.

Etymology: < chest v. + -er suffix¹.