from The Century Dictionary and Cyclopedia
- n. An obsolete form of bottom. Chaucer.
Sorry, no etymologies found.
'I's niver wonder but he's at t' bothom of a bog-hoile.
Take þere þridde part of sowre Dokkes and flour þerto. & bete it togeder tyl it be as towh as eny lyme. cast þerto salt. & do it in a disshe holke  in þe bothom, and let it out wiþ þy finger queynchche  in a chowfer  wiþ oile. & frye it wel. and whan it is ynowhz: take it out and cast þerto suger &c.
"I's niver wonder but he's at t 'bothom of a bog-hoile.