Ké, which was featured in kélchí, is Navajo for shoe(s). (Kélchí referring specifically to mocassins.)
The second word ntsaaí (sometimes nitsaaí) is normally a verb that means (it) is large/huge/big.
If you’re starting to get a hang of these verbs that become objects, you’ll notice the -í at the end. That’s the signal for “the thing (that which is) large/huge/big.”
So together, the word is literally the big shoe.
But in Navajo, it’s a distinct term for a woman’s mocassins. These have similar soles that curve upward around the entire shoe, and the top of the foot covered with hide. Starting at the base of the heel and extending upward near the knee is a wrapping that covers a large portion of the shin. These are commonly white leather wrappings.