There are many different synonyms for the word "or only". Some possible options include "solely", "exclusively", "simply", "merely", "purely", "just", "only", "entirely", and "wholly". Each of these words can be used to convey a similar sense of restriction or limitation, indicating that something is being done or considered in a very narrow or specific way. By selecting the right synonym for the context in question, writers can help to clarify their meaning and ensure that their readers fully understand the limitations or restrictions that are being placed on the argument or idea being presented.