Definitions

from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun Zoology A respiratory aperture, especially.
  • noun Any of several tracheal openings in the exoskeleton of an insect, spider, or other terrestrial arthropod.
  • noun A small respiratory opening behind the eye of most sharks and rays and certain other fishes.
  • noun The blowhole of a cetacean.
  • noun An aperture or opening through which air is admitted and expelled.

from The Century Dictionary.

  • noun An aperture or orifice.
  • noun In zoology, an aperture, orifice, or vent through which air, vapor, or water passes in the act of respiration; a breathing-hole; a spiraculum: applied to many different formations.
  • noun A vent for small explosive outbreaks, produced upon the surface of a still highly heated and at least partially molten lava-stream by the escape of imprisoned vapors. A little cone of ejected clots may gather around it.

from the GNU version of the Collaborative International Dictionary of English.

  • noun (Anat.) The nostril, or one of the nostrils, of whales, porpoises, and allied animals.
  • noun One of the external openings communicating with the air tubes or tracheæ of insects, myriapods, and arachnids. They are variable in number, and are usually situated on the sides of the thorax and abdomen, a pair to a segment. These openings are usually elliptical, and capable of being closed. See Illust. under Coleoptera.
  • noun A tubular orifice communicating with the gill cavity of certain ganoid and all elasmobranch fishes. It is the modified first gill cleft.
  • noun Any small aperture or vent for air or other fluid.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun A pore or opening used (especially by spiders and some fish) for breathing.
  • noun The blowhole of a whale.
  • noun Any small aperture or vent for air or other fluid.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • noun a breathing orifice

Etymologies

from The American Heritage® Dictionary of the English Language, 4th Edition

[Middle English, from Latin spīrāculum, from spīrāre, to breathe.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

Latin spiraculum, from spirare ("to breathe").

Examples

  • A very large dome, built with great care in the centre or pole, contains another small vault as it were rising out of it, and in this is a spiracle, which is right over the altar.

    The City of the Sun

  • At the end, which I was not long in reaching, a breath of wind suggested that what Gunnie had called a spiracle stretched from the roof to this place.

    The Urth of the New Sun

  • A very large dome, built with great care in the cen - tre or pole, contains another small vault as it were rising out of it, and in this is a spiracle, which is right over the altar.

    City of the Sun

  • A very large dome, built with great care in the centre or pole, contains another small vault as it were rising out of it, and in this is a spiracle, which is right over the altar.

    Ideal Commonwealths

  • A very large dome, built with great care in the centre or pole, contains another small vault as it were rising out of it, and in this is a spiracle, which is right over the altar.

    The City of the Sun

  • (In the spiracle is a miniature demibranch, the pseudo-branch.

    Text Book of Biology, Part 1: Vertebrata

  • However, insect body size increases in three-dimensions (length, breadth, and height); hence, body size increases more quickly than spiracle area as insects get larger and larger.

    Evolution

  • At this stage the gills are still external, being apparent as red filaments, and, as usual, branchial filaments are also protruded through the spiracle.

    Notes on New Zealand Fish

  • In a corner of the Kings Palace, it being seated on a rising hill, a cave had long beene made in the body of the same hill, which received no light into it, but by a small spiracle or vent-loope, made out ingeniously on the hils side.

    The Decameron

  • No, he breathes through his spiracle alone; and this is on the top of his head.

    Moby Dick; or the Whale

Comments

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  • ...jet after jet of white smoke was agonizingly shot from the spiracle of the whale...

    - Melville, Moby-Dick, ch. 61

    July 26, 2008