SINCE 1828

An Encyclopædia Britannica Company

Medical Dictionary

pseudoreaction

play

noun pseu·do·re·ac·tion \-rē-ˈak-shən\

Medical Definition of pseudoreaction

: a reaction following the injection of a toxin (as in the Schick test) which is caused by something (as impurities in the test medium) other than the toxin itself

Seen and Heard

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

show

WORD OF THE DAY

flagrant

play

conspicuously offensive

Words at Play

alt-599ca1388698f

Drawing a Conclusion About "Sketchy"

How did "sketchy" come to describe creeps?

2-pairs-of-scissors

What's the Singular of 'Scissors'?

A tricky, double-edged word origin.

a-woman-waits-at-the-end-of-a-gloomy-pier-does-she-wait-for-charon-the-ferryman-to-the-underworld-it-is-dark-but-she-carries-a-parasol

Great Words for Twilight and Darkness

Words for the goth in all of us

bunch-of-yellow-balloons-lit-by-the-sun

Helium: This Word Brought to You by a Solar Eclipse

And by the Sun, with some help from Greek.

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

time-traveler-quiz-which-word-came-first

Time Traveler Quiz: Which Word Came First?

Which word entered the English language first?

Take the quiz

Name More Food!

Test your knowledge of food vocabulary!

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