General:
* Cool: (1940s) Originally meant "calm, composed," now used to express approval, attractiveness, or stylishness.
* Dope: (1930s) Originally meant "narcotic," now used to express something excellent or impressive.
* Awesome: (1960s) Originally meant "inspiring awe," now used to express enthusiasm or excitement.
* Rad: (1970s) Originally meant "radical, extreme," now used to express something cool or excellent.
* Chill: (1950s) Originally meant "to relax," now used to express calmness, tranquility, or to relax.
* Hangry: (2000s) A blend of "hungry" and "angry," now used to describe someone who is irritable because they're hungry.
* Lit: (2010s) Originally meant "intoxicated," now used to describe something exciting, enjoyable, or impressive.
* Savage: (2010s) Originally meant "fierce," now used to describe something brutal, intense, or impressive.
* Woke: (2010s) Originally from African-American Vernacular English, now used to describe someone who is aware of and attentive to important social issues, especially those related to racial and social justice.
* Yeet: (2010s) Originally an exclamation of excitement, now used to describe throwing something forcefully or to express enthusiasm.
* Gucci: (2010s) Originally a high-end fashion brand, now used to describe something good, excellent, or fashionable.
* Flex: (2010s) Originally meant to show off, now used to describe something impressive or showy.
* Slay: (2010s) Originally meant to kill, now used to describe doing something exceptionally well.
Tech:
* Bug: (1940s) Originally a term for a malfunction in a mechanical device, now used to describe errors in computer software.
* Crash: (1950s) Originally meant to collapse suddenly, now used to describe a computer malfunction that causes it to stop working.
* Hack: (1960s) Originally meant to cut or chop something, now used to describe a clever solution to a problem or to gain unauthorized access to a computer system.
* Spam: (1970s) Originally a brand of canned meat, now used to describe unsolicited electronic messages.
* Troll: (1990s) Originally a mythological creature, now used to describe someone who posts inflammatory or provocative messages online.
Specific to a region or culture:
* Ghetto: (1930s) Originally meant "a section of a city inhabited by a specific group of people," now used to describe something that is of low quality or associated with poverty.
* Bohemian: (1800s) Originally meant "from Bohemia," now used to describe someone who is unconventional and artistic.
* Hooligan: (1800s) Originally a name for a type of mischievous person, now used to describe someone who is violent or disruptive.
* Hipster: (1940s) Originally meant "a person who is fashionable and aware of trends," now used to describe someone who is trendy, nonconformist, and often ironic.
This is just a small sample of words that have entered the dictionary from slang. New slang words are constantly being created and evolving, and some of them may eventually make their way into the mainstream lexicon.