thorax

noun

tho·​rax ˈthȯr-ˌaks How to pronounce thorax (audio)
plural thoraxes or thoraces ˈthȯr-ə-ˌsēz How to pronounce thorax (audio)
1
: the part of the vertebrate body between the neck and the abdomen
If you count the vertebrae in the necks and thoraxes of mice and chickens, you will find that a mouse has seven neck and 13 thoracic vertebrae, a chicken 14 and seven, respectively.Matt Ridley
also : thoracic cavity
The thorax is evaluated for fluid at the flanks and for pneumothorax anteriorly. Christoper L. Moore
2
: the middle of the three chief divisions of the body of an insect
Of nearly a million described species of insects, none has a biramous appendage, and nearly all have exactly three pairs of limbs on the thorax.Stephen Jay Gould
This haunting pitch issues from drum tissue stretched over the thorax of the male annual cicada …Ted Williams
also : the corresponding part of a crustacean or an arachnid
The brown recluse spider … is brown and has fuzzy body hair and a dark violin- or pear-shaped band on the dorsum of its thorax. Peter F. Weller

Example Sentences

Recent Examples on the Web The parasite's method is diabolical: A fly dive-bombs an ant and quickly inserts an egg in the ant's thorax. Discover Magazine, 29 June 2010 When researchers once attempted to pry apart a mating pair, the male’s abdomen was ripped from the thorax, but the genital coupling remained intact. Carl Engelking, Discover Magazine, 17 Apr. 2014 Crystals had started to progress over its head and thorax. Henry Wismayer, Anchorage Daily News, 30 Aug. 2022 Crystals had started to progress over its head and thorax. Henry Wismayer, Anchorage Daily News, 30 Aug. 2022 Crystals had started to progress over its head and thorax. Henry Wismayer, Anchorage Daily News, 30 Aug. 2022 Wheel bugs get their name from the shape of their thorax, the middle body segment where all legs and wings arise. Miri Talabac, Baltimore Sun, 6 Oct. 2022 The insect, formally known as Plecia nearctica, are small black flies with a red thorax, according to a report from the University of Florida. Garfield Hylton, Orlando Sentinel, 13 Sep. 2022 Crystals had started to progress over its head and thorax. Henry Wismayer, Anchorage Daily News, 30 Aug. 2022 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'thorax.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Word History

Etymology

Middle English, from Latin thorac-, thorax breastplate, thorax, from Greek thōrak-, thōrax

First Known Use

15th century, in the meaning defined at sense 1

Time Traveler
The first known use of thorax was in the 15th century

Dictionary Entries Near thorax

Cite this Entry

“Thorax.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/thorax. Accessed 28 Mar. 2023.

Kids Definition

thorax

noun
tho·​rax ˈthō(ə)r-ˌaks How to pronounce thorax (audio)
ˈthȯ(ə)r-
plural thoraxes or thoraces ˈthōr-ə-ˌsēz How to pronounce thorax (audio)
ˈthȯr-
1
: the part of the body of a mammal between the neck and the abdomen
also : its cavity in which the heart and lungs lie
2
: the middle of the three main divisions of the body of an insect

Medical Definition

thorax

noun
plural thoraxes or thoraces ˈthōr-ə-ˌsēz, ˈthȯr- How to pronounce thorax (audio)
1
: the part of the mammalian body that is situated between the neck and the abdomen and supported by the ribs, costal cartilages, and sternum
2
: the middle of the three chief divisions of the body of an insect
also : the corresponding part of a crustacean or an arachnid
Last Updated: - Updated example sentences
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