eccentricityEnglishOxford Dictionary of Englisheccentricity /ˌɛksɛnˈtrɪsɪti , ˌɛks(ə)nˈtrɪsɪti / ▸ noun (plural eccentricities) [mass noun] 1 the quality of being eccentric: the eccentricity of his views. ▪ (eccentricities) [count noun] an eccentric act or habit: her eccentricities were amusing rather than irritating. 2 technical deviation of a curve or orbit from circularity. ▪ [count noun] a measure of the extent of deviation from circularity: Halley's Comet has an eccentricity of about 0.9675.