SINCE 1828

An Encyclopædia Britannica Company

periplasm

play

noun peri·plasm \ˈper-ə-ˌpla-zəm\

Definition of periplasm

: the region in a gram-negative bacterium between the plasma membrane and an outer surrounding membrane that contains especially enzymes and a thin layer of peptidoglycan

periplasmic

play \ˌper-ə-ˈplaz-mik\ adjective

First Known Use of periplasm

1961

Seen and Heard

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

show

WORD OF THE DAY

advise

play

to counsel, recommend, or inform

Words at Play

alt-59721dd897313

The 'Best' Way to Sign Off On An E-mail

Give them your best

Words and Phrases That Come from the Dinner Table

Fill your plate with these surprising food words

ghost-being-disinvited-from-party

'Disinvite' or 'Uninvite'?

A disinvited guest is an uninvited problem

alt-596f730ceb5ae

Words We're Watching: 'Scoby'

Kombucha lovers unite.

Ask the Editors

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'

How Often Is 'Biweekly'?

Don't get us started on 'bimonthly'

video-irregardless-grammar-peeve-blend-of-the-synonyms-irrespective-and-regardless

Irregardless

It is in fact a real word (but that doesn't mean you should use it).

video-moose-goose-weird-plurals

Weird Plurals

One goose, two geese. One moose, two... moose. What's up with that?

Word Games

The Emoji Quiz

Think you’re an emoji 👓 expert? Let’s see 🤔

Take the quiz

A Game of Thrones Word Quiz

In the Game of Thrones quiz, you learn some new vocabulary. (It’s quite safe, really. You will not die.)

Take the quiz

Name That Thing

Name That Thing

Test your visual vocabulary with our 10-question challenge!

Take the quiz

Bee Cubed

Listen to the words and spell through all three levels.

Play the game