Si′-pah ‘straight’ is from Clackamas Upper Chinookan
On the authority of his buddy and fellow “Stevens Treaties” translator Benjamin Franklin Shaw, George Gibbs tells us a word si′-pah ‘straight (like a ramrod)’.

Gibbs 1863:23
This is said to be a “Wasco” Upper Chinookan word, a label I would associate with Kiksht/”Wishram”, the Chinookan language traditionally spoken the farthest upstream on the Columbia River.
It’s said to be “of only local use”, and we haven’t found anyone else documenting it in actual Chinuk Wawa. Nonetheless, if Gibbs saw it as legitimate CW, it’s worth knowing more about this word. So I went looking for confirmation of its source, and was mildly surprised.
This appears to actually from Clackamas Upper Chinookan, the Chinookan language of the Willamette River area — call it the Portland, Oregon vicinity. So it’s what you might call straight Chinook.

Straight Chinook paisley pants (image credit: Five Story NY)
In the publication “Clackamas Chinook Texts”, I:93, I found a-saybá, and on page 213 sáybá. I’ve not found this word/stem/root in the other Chinookan languages…
Apparently ‘straight’ is wuq’ in all of Lower Chinookan, and náwit in Kiksht. (Which I expect is related to Chinook Jargon’s word nawítka ‘truly; yes’.)
I infer that in Jargon, this word for a ‘straight’ object was pronounced sáypá, that is, with some possible variation between first-syllable and second-syllable main stress placement. We see such variation pretty commonly on some Jargon words, e.g. the similar-sounding sáyá ‘far (away)’. I
If memory serves, some of the few times I’ve heard people try to use this word nowadays, they’ve pronounced it like *sípa*, mis-reading the cues in Gibbs 1863.
It actually seems pretty useful to me to have a word for ‘straight’ (that is, long and skinny). I wonder if this southern-dialect word might ever come back in, say, Grand Ronde speech.
