Learner's definition of DOUBTLESS
[more doubtless; most doubtless]
without doubt or with very little doubt
— used when you are making a statement that you think is certainly or almost certainly true
She was doubtless [=unquestionably, no doubt] the smartest person in her class.
There will doubtless be many more issues to deal with before this is over.
The car accident will doubtless result in a lawsuit.