Definition of spicule in US English:



  • 1technical A minute sharp-pointed object or structure that is typically present in large numbers, such as a fine particle of ice.

    • ‘A general overview on the structural organization of the proteinaceous filament inside spicules is presented.’
    • ‘The spicules of bone revealed the characteristic corallike branching.’
    • ‘The tarpaulin that covers the entrance is gashed in several places, undoubtedly caused by the ice spicules flying at speeds that made them deadly projectiles.’
    • ‘The possibility of obtaining some structural information on the filaments inside the spicules can certainly give a more realistic picture of their organization.’
    • ‘The sharp spots in the diffraction patterns shown in Fig.5 indicated that the protein units forming the central filaments inside the spicules must be organized with a very high degree of order.’
    1. 1.1Zoology Each of the small needle-like or sharp-pointed structures of calcite or silica that make up the skeleton of a sponge.
      • ‘Recently spicules from sponges of the class Hexactinellida have been identified in Ediacaran age rocks.’
      • ‘G. cydonium spicules show equatorial spots up to the third order, which are consistent with a very regular hexagonal arrangement of protein units aligned along the spicule axis.’
      • ‘Sponge spicules are also an abundant constituent of the rhythmites.’
      • ‘Pillow lava and marine sponge spicules found in the contact zones between individual layers of the Columbia River Basalt suggest that these lava layers flowed out under water and that the water was ocean water, not freshwater from a lake.’
      • ‘Another factor that must be taken into account to interpret the different behavior of the various spicules is the morphology of the spicules investigated.’
      needle, quill, bristle, barb, spike, prickle
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  • 2Astronomy
    A short-lived, relatively small radial jet of gas in the chromosphere or lower corona of the sun.

    • ‘Although relatively small compared to full scale solar flares, spicules are interesting for the same reasons: they may contribute to the solar wind.’
    • ‘Penetrating the chromosphere are spikes of gas that rapidly jet upwards and then fall back again; these are termed spicules.’


Late 18th century: from modern Latin spicula, spiculum, diminutives of spica ‘ear of grain’.