Dingbat (noun)

1. A person who is silly, foolish, or eccentric.
2. A stupid or crazy person, a simpleton.
3. A small simple geometric symbol often used in typography.

Origin:

Perhaps from the sound made by a bell or a meaningless sound made to indicate emphasis or to fill a pause, or from the word ding, meaning "a ringing sound".

Examples:

1. He"s such a dingbat, he can"t even tie his shoes.
2. She"s a total dingbat, she can"t even remember where she left her keys.
3. The dingbat is used to create bullet points in a document.
4. The typographer used dingbats to create a playful and interesting design.
5. The dingbat font was used to create a symbol that represented the brand.