► maybeused to say that something may happen or may be true, but you are not certain: Maybe I’ll buy myself a new dress. Maybe this wasn’t such a good idea.
► perhaps formal perhaps means the same as maybe but is used especially in writing: Perhaps the architects can think of a better way to design the seating. The footprints belonged to a large cat – a tiger, perhaps.
► probably used when saying that you are fairly sure something is true or will happen, but not definite: I’ll probably be a little late getting home because the traffic is bad.
► possibly used when saying that something may be true, but you do not have enough information to be sure: The swimmer is competing in the Olympics, possibly for the last time.
► conceivably formal if something can conceivably happen or be true, it is possible but unlikely: The characteristics of this mental illness are so general that conceivably just about everyone could be diagnosed as mentally ill.