sinusoidPronunciation: /ˈsʌɪnəsɔɪd/Definition of sinusoid noun 1another term for sine curve. 2 Anatomy a small irregularly shaped blood vessel found in certain organs, especially the liver. Derivatives sinusoidalPronunciation: /-ˈsɔɪd(ə)l/ adjective sinusoidallyPronunciation: /-ˈsɔɪd(ə)li/ adverb Origin: early 19th century: from French sinusoïde, from Latin sinus (see sinus)sinusoid in other Oxford dictionaries Definition of sinusoid in the US English dictionary