An adverb used to cautiously suggest a possibility; often appears as 'might/may possibly'.
もしかすると彼が忘れているのかもしれない。
He might have forgotten, perhaps.
もしかすると電車が遅れるから、早めに出よう。
The train might be delayed, so let's leave early.
もしかすると、それは勘違いだと思う。
I think that might be a misunderstanding.