Lit. "That which is a little hole through something", probably from verb chekulk, "is a little hole through something".
Mesa Grande dictionary seems to contain a typo, writing this word as kuchkulk in one section and kuchkullk in another. If it is truly a small hole, we would expect the noun to come from the "small" version of the verb, chekulk. To refer to larger holes, kuchkullk could probably be used, from chekullk "is a (large) hole through something".
Cuevas' pronunciation kuuchullk deviates significantly from the Mesa Grande, but is similar enough that it is probably based on the same verb and has the same meaning.