SINCE 1828

An Encyclopædia Britannica Company

sed

abbreviation

Definition of sed

sedimentation

Medical Dictionary

SED

abbreviation

medical Definition of SED

skin erythema dose

Seen and Heard

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

show

WORD OF THE DAY

loath

play

unwilling or reluctant

BROWSE DICTIONARY

secus

secy

sed

sedan

Sedan

Test Your Vocabulary

Odd Habits and Quirks Quiz

Which of the following best describes an easily irritated person?

Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ

Word Winder's CrossWinder

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ

Words at Play

alt-5adf93a49b0b2

The Fossil Encased in "Case In Point"

"In point" only lives in this phrase.

alt-5adf5d017e6bf

‘Sleight’ or ‘Slight’ of Hand?

Watch closely and be amazed.

alt-5ade0f1ca7a0c

'Complement' vs. 'Compliment'

The distinction is clear (now).

Words from Letters in the Greek Alphabet

When English borrows from another alphabet

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

Name That Thing

Name That Thing

Test your visual vocabulary with our 10-question challenge!

Take the quiz

Word Winder's CrossWinder

Word Winder's CrossWinder

A game of winding words.

Play the game