orthographic depth
Definition - A scale used to describe the correspondence between sounds and written characters in alphabetic languages, where the less correspondence there is between letters and sounds the greater the orthographic depth.

For example, it ranges from "shallow" writing systems, such a Finnish, where there is a high correspondence between letters and sounds, to "deeper" writing systems, such as English, where there is lower correspondence between the letters written and the sounds produced (e.g. eight and tough).

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