Arachnida

noun plural
Arach·​ni·​da | \ ə-ˈrak-nəd-ə How to pronounce Arachnida (audio) \

Medical Definition of Arachnida

: a large class of arthropods that are mostly air-breathing by means of trachea or book lungs, that include the spiders and scorpions, mites, and ticks, and that have a segmented body divided into two regions of which the anterior bears four pairs of legs but no antennae

Other Words from Arachnida

arachnid \ -​nəd How to pronounce arachnid (audio) \ adjective or noun

Comments on Arachnida

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

WORD OF THE DAY

to make a temporary encampment

Get Word of the Day daily email!

Test Your Vocabulary

Musical Words Quiz

  • gramophone
  • Which word describes a musical performance marked by the absence of instrumental accompaniment?
True or False

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

TAKE THE QUIZ
SCRABBLE® Sprint

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

TAKE THE QUIZ
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!