Likely
Definition 1 of 4
Pro Tip 1/2
Predictive Use
Use 'likely' when predicting future events based on current evidence. Given the dark clouds, it's likely that we'll need umbrellas.
Pro Tip 2/2
Emotional Distance
'Likely' adds a sense of detachment compared to saying something is certain. It's likely he forgot the meeting, rather than he definitely forgot.