SINCE 1828

An Encyclopædia Britannica Company

Medical Dictionary

arsenic acid

noun ar·sen·ic acid \ är-ˌsen-ik- \

medical Definition of arsenic acid

: any of three arsenic-containing acids that are analogous to the phosphoric acids

Seen and Heard

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

show

WORD OF THE DAY

slew

play

a large number

Words at Play

All the Hits

8 obscure words for bodily harm

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).

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

Dictionary Devil

Dictionary Devil

The dictionary has been scrambled—can you put it back together?

Play the game