Search: karabiner
Why: The 40 oz. wide Klean Kanteen comes with a loop cap that clips right onto a Kanteen® S-Biner.
Answer: It's from German!
Shortened from the German word Karabinerhaken, "carbine hook" - that is, one used to attach a carbine rifle to a belt
Source: Glossary of Caving Terms
The More You Know: Why does German capitalize seemingly arbitrary words? Well, for one, they're all nouns. ALL nouns are capitalized, and, of course, proper names and titles (Frietag, Deutsche Bank, Frau Jones). They do not, however, capitalize adjectives of nationality: "American car" is amerikanisches Auto; "German wine" is deutscher Wein. They don't capitalize "I" (ich), but they do capitalize all formal forms of "you" - Sie, Ihnen, Ihr. It's all very complicated. There's a whole Bund für vereinfachte rechtschreibung ("Federation for Simplified Spelling") that regulates things like this; new rules went into effect as recently as 2005.
