We don't have synonyms for allonge yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are allong and alonge.
"they were waiting for me in the drawing-room, which is a very large room, stretching along the entire front of the house, with three long windows reaching down to the floor. -- Doyle"
"they were waiting for me in the drawing-room, which is a very large room, stretching along the entire front of the house, with three long windows reaching down to the floor. -- Doyle"