a man who is much concerned with his dress and appearance
"The new guy at work is such a dude, spending hours every morning choosing between three different pairs of socks to match his tie."
A man, generally a younger man.
"The group of guys at the park were all young dudes enjoying their summer break."
In plain English: Dude is an informal way to call someone you know well, often used as a friendly greeting or expression of surprise.
"Hey dude, did you catch the game last night?"
To address someone as dude.
"Hey dude, can you help me move these boxes?"
In plain English: To dude someone is to act as if you are their close friend while actually being fake and insincere about it.
"After weeks of worrying, she finally dude that her friend was just having fun and didn't mean any harm."
A term of address, usually for a man, conveying awe, excitement, surprise, annoyance, etc.
"Dude! Did you see that incredible goal just scored?"
Dude likely originated in 18th-century American slang as a shortened form of "doodle," referring to the character from the song "Yankee Doodle." First recorded in New York City around 1883, it initially served as an insult for a fastidious man or fop before evolving into its modern meaning.