isosbestic pointPronunciation: /ˌʌɪsə(ʊ)sˈbɛstɪk/Definition of isosbestic point noun Chemistry a wavelength at which the absorption of light by a mixed solution remains constant as the equilibrium between the components in the solution changes. Origin: early 20th century: isosbestic from iso- 'equal' + Greek sbestos 'extinguished' (from sbennunai 'quench') + -icisosbestic point in other Oxford dictionaries Definition of isosbestic point in the US English dictionary