fokozatos átmenet angolul

cline [clines]▼noun
[UK: ˈklaɪn] [US: ˈklaɪn]

intergradation [intergradations]▼noun
[UK: ˌɪntəɡreɪdˈeɪʃən] [US: ˌɪntɚɡreɪdˈeɪʃən]