áysh is related to ayáxwul ‘borrow/lend’…also to húyhuy ‘trade’?
There’s an obscure & obsolete Chinook Jargon word for ‘lend; borrow’ that came from “Chihalis” (Lower Chehalis Salish), said George Gibbs in 1863. 
This is probably correct; Gibbs knew his stuff pretty darn well, when it came to the tribal languages. As a government Chinuk Wawa interpreter, he had lots of personal experience talking with Native people and asking them for useful information.
But, as I say — this was probably correct. It’s certainly not a Chinookan word, but proving it’s Salish takes a bit of work.
In more recent times, documentation of the 4 sister SW Washington Salish (“Tsamosan”) languages only shows words for ‘borrow’ and ‘lend’ that are, to a linguist’s eye, all based on a different-looking root, a Proto-Tsamosan form *kʷúl:
- In modern Lower Chehalis, the only word we know in this semantic range is čáɬ[-]č[-]ən, which the elders translated as ‘to give; to loan/lend; to hand (pass)’. We don’t know a word for ‘borrow’ in L.C.
- Quinault uses ~ čúlja, meaning both ‘lend’ and ‘borrow’.
- Upper Chehalis has čó:yaʔ ‘borrow; loan to’.
- Cowlitz kʷú[-]st[-]m is ‘borrow; lend; rent’.
All of that variation among /u ~ a/, /kʷ ~ č/, and /ɬ ~ l ~ y ~ Ø/ (that last symbol meaning that the “L”-like sound dropped out) is pretty standard fare in SW WA Salish. Aert H. Kuipers’ 2002 “Salish Etymological Dictionary” reconstructs several such alternations all the way back to ancient Proto-Salish, and his P-S root for ‘borrow’ (only that meaning — not ‘lend’!) is indeed *kʷul.
On that topic, another super-frequent alternation in SW SW Salish is /kʷ ~ xʷ/, so the earlyish Lower Chehalis-sourced form in Gibbs’s Chinook Jargon dictionary, that < a-yáh-whul >, might very well reflect a historical change of that same *kʷul to xʷul.
In that event, the beginning of the Low. Cheh. word then suggests Proto-Salish (and Proto-Tsamosan) *ʔay ‘to (ex)change, barter; pay; meet’, which we’ve found in the Low. Cheh.-to-CJ loan áysh ‘to accompany’, reported by Franz Boas in 1892.
You’d be right to ask me what’s going on with the < áh > in this word. It does match one of the many forms of the “Stem Extender” suffix in Lower Chehalis. But that -á doesn’t occur between 2 joined verb roots in my experience of that language; it’s normally followed by a “lexical suffix” instead.
Therefore, I’m more comfortable understanding the sequence < a-yáh- > as another typical SW WA Salish phenomenon, the development of a CVC (consonant – vowel – consonant) root *ʔay into CVCV, *ʔaya.
Now, Lower Chehalis ‘accompany’, ʔáysh, was a metaphor, ‘to swap feet with’ someone. Thus, our Jargon < a-yáh-whul > would appear to come from a serial verb (those exist in these Salish languages), *ʔaya+kʷul meaning ‘to swap (and) (lend/)borrow’.
(The serial-verb stem is *ʔaya+kʷul, and if you remember to add the “silent 3rd person perfective subject” pronoun of Low. Cheh., it’s pronounceable as a word, ‘(s)he/they swapped (and) (lent/)borrowed’.)
An interesting outcome of our analysis is that in modern times, Lower Chehalis has preserved 2 very different-sounding developments of the Proto-Salish root *kʷul:
- xʷul
- čáɬ
Bonus fact:
All of this in turn brings up the tantalizing possibility that Chinuk Wawa’s famous word húyhuy ‘to trade’ has a SW WA Salish source.
This would be news.
Up to this point, we’ve only had speculative etymologies, that that word comes from:
- “Canadian (Métis) French” oui oui ‘yes, yes’ (Alexander Caulfield Anderson’s personal comment to Geo. Gibbs),
- and/or some sort of unattested & unexplained reduplication of Nuuchahnulth/Nootka Jargon ḥaʔuyi ~ ḥaaʔuy ‘to trade, barter, swap’ (Confederated Tribes of Grand Ronde CW dictionary).
Knowing what we know of SW WA Salish historical sound changes and grammar, a normal reduplicated form of the root previously shaped *kʷúl could be ~ *xʷúy•xʷuy.
Which for all of our purposes sounds exactly like our CW húyhuy.
Such a SW WA Salish word ought to mean something like ‘borrow(ing) (and lending) all over the place; borrowing (& lending) and borrowing (& lending)’.
