functional load
noun Linguistics.
the relative frequency of occurrence of words that are differentiated in one and the same position by only one distinctive feature. In English, the opposition of voiced and voiceless th has a low functional load being used only to distinguish such pairs as ether and either, or wreath and wreathe.
Also called functional yield.
Dictionary.com Unabridged
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019