etymologies of "dukkha"

Dear All,

Recently I received the following enquiry about the etymology of "dukkha":

<< Since kha is the root for khanti I wondered if "lack of patience" would
be an adequate transcription for dukkha. >>

Has anyone ever come across the root "kham" (to be patiient; to endure) for
the "kha" part of "dukkha"? The derivation given at Vism XVI.16 has the
"kha" part in the sense of "empty" which Aggavaṃsa curiously places under
the root "khi" {khi or khī khaye = to destroy}. I wonder if "kham" (with
the -m truncated) would have been a better choice for the ancient
etymologists. i.e., "dukkha" in the sense of  "hard to endure" instead of
"bad-empty".

Apte's Sanskrit-English dictionary gives the following 3 etymologies for
"duḥkha":

[ duṣṭāni khāni yasmin, duṣṭaṃ khanati khan-ḍa, duḥkh-ac vā Tv.]
I think the root "khan" here has the sense of "to dig".

I'd be interested to know of other etymologies. Another one I saw gives
duḥkha as a Prakritixed "duḥ-stha" (unsteady) in MW's dictionary. Wikipedia
also has something on the etymology of dukkha

Best wishes,

Jim