From Longman Dictionary of Contemporary Englishin all seriousnessin all seriousnessa) spoken used to show that what you say next is not a joke, especially because it is important SYN seriously In all seriousness, if Tom does resign, a lot of other people will start leaving too. b) in a way that is not joking ‘Playing with Richie was the highlight of my musical career, ’ said Sonny in all seriousness. → seriousness
Examples from the Corpus
in all seriousness• The material on which the congressional record is founded is done there every day in all seriousness.• Nothing is so funny as something done in all seriousness.• Did you feel, in all seriousness, you were dying?• He asked me, in all seriousness, if I would marry him next week.• She had heard someone say, in all seriousness, that women would never make good golfers because of the shape of their bodies.• We wonder in all seriousness if alcohol had anything to do with it. 