functional load

American  

noun

Linguistics.

1. 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.

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Example Sentences

So Bouchard-Côté's team tested the "functional load hypothesis," which says that sounds that are more important for distinguishing two words are less likely to change over time.

From Scientific American