The Latin word castra, originally meaning "camp," came (in Britain) to signify a fortified town, and was adopted into the various dialects of English as caster, Chester, or cester; the first being the distinctively N. Eastern, the last the S. Western form.
Amongst these, however, must be named the high authority of Professor Skeat. See 'Cambs. Place-Names.'
Pearson's 'Historical Maps of England' gives a complete list of these.