;gen. ceastre; f. The chalk city. Camden thinks it is Tadcaster, in Yorkshire; idem, ut opinatur clarus Camdenus, quod hodie Tadcaster in agro Eboracensi, sic olim vocatum a ealce ibidem copiose effossa, Som. Ben. Lye.
Cite the scanned version of the original dicionary like this:
Bosworth, Joseph. "Cealca ceaster." An Anglo-Saxon Dictionary: Based on the Manuscript Collections of the Late Joseph Bosworth. Ed. Thomas Northcote Toller. Oxford: Clarendon Press, 1898. 147.