how can she be so cheerful at six o'clock in the morning?
a cheerful voice
Causing happiness by its nature or appearance
a chatty, cheerful letter
the room was painted in cheerful colors
being full of or promoting cheer; having or showing good spirits; "her cheerful nature"; "a cheerful greeting"; "a cheerful room"; "as cheerful as anyone confined to a hospital bed could be"
pleasantly (even unrealistically) optimistic
(cheerfulness) the quality of being cheerful and dispelling gloom; "flowers added a note of cheerfulness to the drab room"
Cheering is the uttering or making of sounds encouraging, stimulating or exciting to action, indicating approval or acclaiming or welcoming persons, announcements of events and the like.
(Cheerfulness) Happiness is a state of mind or feeling characterized by contentment, love, satisfaction, pleasure, or joy. A variety of biological, psychological, religious, and philosophical approaches have striven to define happiness and identify its sources.
Noticeably happy and optimistic; Bright and pleasant
(CHEERFULNESS) "Relaxing with oneself and picking up on the possibilities of basic goodness." "...you can pick up on the possibilities of Basic Goodness and cheer yourself up." (see "Speech") (pg 80)
A sign that is shown by fans between matches in a tournament to hype or show appreciation for a team or player in a witty way. (Example cheerfuls from MLG Anaheim)