The U.S. Merriam-Webster dictionary has added 640 new words and new definitions to its index, reflecting changing uses of the English language.

“Snowflake’’ now also means someone who is too sensitive, while “peak’’ formally can be defined as something at the height of popularity or usage.

“Stan’’ refers to an obsessive fan. 

Compound terms have also entered the dictionary, such as “garbage time,’’ meaning the final part of a sports game in which one side has an insurmountable lead. 

“Screen time’’ refers to the amount of time one spends staring at a mobile phone or tablet. 

The changing nature of the business world has also influenced the dictionary, which now includes terms like the “gig economy,’’ referring to temporary work, and “vulture capitalism,’’ which refers to aggressive buying of distressed companies. 

“The English language never sleeps, and neither does the dictionary. 

“Each word follows its own path at its own pace before its use is widespread enough to be included in a dictionary,’’ Merriam-Webster said in a statement.

There are also a bunch of new words from science, including terms that reflect societal shifts. “Top surgery’’ and “bottom surgery’’ are both terms from gender confirmation operations, as transgender visibility expands.