to eat away below, to sap; subedere :-- Ðæt mennisce mód bið undereten and áweged of his stede ðonne hit se wind strongra geswinca ástyroþ, Bt. 12; Fox 36, 17.
Cite the scanned version of the original dicionary like this:
Bosworth, Joseph. "under-etan." An Anglo-Saxon Dictionary: Based on the Manuscript Collections of the Late Joseph Bosworth. Ed. Thomas Northcote Toller. Oxford: Clarendon Press, 1898. 1097.