[ sahy-nuh-soid ]
/ ˈsaɪ nəˌsɔɪd /

noun Mathematics.

a curve described by the equation y = a sin x, the ordinate being proportional to the sine of the abscissa.

Nearby words

  1. sinus of vena cava,
  2. sinus pause,
  3. sinus rhythm,
  4. sinus sabaeus,
  5. sinusitis,
  6. sinusoidal,
  7. sinusoidal projection,
  8. sinusotomy,
  9. sinǔiju,
  10. sion

Origin of sinusoid

First recorded in 1815–25; sinus + -oid Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for sinusoid


/ (ˈsaɪnəˌsɔɪd) /


any of the irregular terminal blood vessels that replace capillaries in certain organs, such as the liver, heart, spleen, and pancreas
another name for sine curve


resembling a sinus

Word Origin for sinusoid

C19: from French sinusoïde. See sinus, -oid

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for sinusoid


1823 in mathematics; 1900 in physiology, from sinus + -oid. Related: Sinusoidal.

Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for sinusoid


[ sīnə-soid′, -nyə- ]


Any of the venous cavities through which blood passes in various glands and organs, such as the adrenal gland and the liver.


Resembling a sinus.
Related formssi′nu•soidal (-soidl) adj.

The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.