CT form *quš. Although lost in Chuvash, it may be preserved in Chuvash for duck: kăvakal, which could potentially be reconstructed as "blue+bird". Sakha kötör can be broken down as "fly+er"; it preserves the form kus to mean "duck". Reconstruction of final *-š depends on analysis of the *l~š alternation.

Chuvash kayăk means animal generally (see deer for related forms), to which an participle meaning "flying" can be added, or the orphan word kĕšĕk.

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