2 if something is reasonable, there are good reasons for thinking that it is true or correct
It’s reasonable to assume that these measures will prove successful.
They had reasonable grounds for taking action.
beyond (a) reasonable doubt (=so that there is little possibility of something not being true): The prosecution must prove their case beyond reasonable doubt.
a reasonable explanation/excuse: I’m sure there’s a perfectly reasonable explanation for his absence.
Synonyms and related words