Addorsed is a rather obscure word in English, but it means two objects placed back-to-back or facing in opposite directions. Although there aren't any exact synonyms for this word, there are several similar expressions that can convey a similar meaning. For instance, you could use the term "confronting" to describe two objects facing each other. Alternatively, you could use the word "juxtaposed" to suggest that the objects are side by side but facing in opposite directions. "Back-to-back" or "opposing" are also valid options, although they don't convey quite the same level of technical precision as the word "addorsed".