SINCE 1828

An Encyclopædia Britannica Company

Wi-Fi

certification mark \ ˈwī-ˈfī \

Definition of Wi-Fi

—used to certify the interoperability of wireless computer networking devices

Seen and Heard

What made you want to look up Wi-Fi? Please tell us where you read or heard it (including the quote, if possible).

show

WORD OF THE DAY

cathexis

play

investment of mental or emotional energy

Words at Play

alt-5ade0f1ca7a0c

'Complement' vs. 'Compliment'

The distinction is clear (now).

Words from Letters in the Greek Alphabet

When English borrows from another alphabet

alt-5ada140ed3e28

'Preventive' or 'Preventative'?

alt-5ad8fc71357ed

Words We're Watching: 'Bluebeard,' the Verb

No, it's not a coiffure trend

Ask the Editors

2017 Word of the Year: Behind the Scenes

How we chose 'feminism'

video-title-words-of-the-year-1066

Words of the Year: 1066

Or, Why Pig Meat is Called 'Pork' and Cow Meat is Called 'Beef'

video-literally

Literally

How to use a word that (literally) drives some people nuts.

video-his-or-her

Is Singular 'They' a Better Choice?

The awkward case of 'his or her'

Word Games

Odd Habits and Quirks Quiz

Test your knowledge of strange human behaviors.

Take the quiz

cats-on-impossible-timber

More Confusing Words—Quiz

How many of these commonly confused words do you know?

Take the quiz

True or False?

Test your knowledge - and maybe learn something along the way.

Take the quiz

Word Winder's CrossWinder

Word Winder's CrossWinder

A game of winding words.

Play the game