Shoulder
Instant Phonetic Englishization: shee_pah_tl!
Lolly’s second time saying the word is the one to imitate. The first one and the third one each have very light ejective releases of the word-final latreral affricate, which we know for sure is an ejective, because of Lolly’s second time saying the word.
Mrs. Peterson evidently did not say any Milluk word like this in her work with Melville Jacobs.