truncation or mot-valise

In German common-parlance, there's a whole array of pet-names, abbreviations, whose practice does not seem to have an analogue in other languages—outside of jargon, where trying to make acronyms pronounceable reigns, portmanteaux or celebrity nicknames.
To name a few: there is Abo for Abonnement, a French borrowing for subscription, Azubi for Auszubildener, an apprentice, the plural Elis for the ever dual Eltern for parents, Deo for deodorant, Bio for biological or organic, and earlier Ami for Americans and Stasi for Staatssicherheitsdienst. I was exposed to a new example recently—or so I thought. Miliz, it turns out, is the full and proper term for militants or a militia. I recall once watching sail boats out on the bay with some friends when a stranger asked if he could borrow our binocs. Of course, I obliged but wondered ever since where by what leave he got dropping the rest of the word.