Someone who is cheerful is happy and shows this in their behaviour.
cheery
Paddy was always cheerful and jolly.
帕迪总是很高兴,很开心。
Something that is cheerful is pleasant and makes you feel happy.
The nursery is bright and cheerful, with plenty of toys.
该托儿所明亮宜人,有许多玩具。
If you describe someone's attitude as cheerful, you mean they are not worried about something, and you think that they should be.
There is little evidence to support his cheerful assumptions.
几乎没有证据来支持他乐观的设想。