For most of my life 'till about a couple of years ago, I had only seen the spelling orangutan written to describe those delightful red-headed apes from the tropical forests of Borneo. Lately, though, I've increasingly been seeing a strange spelling in certain scientific publications I read: orang-utan, with a hyphen. Is there a particular reason why this hyphen was added? It's strange, because usually in English, words evolve to have their hyphens and diacriticals omitted, not added.
Perhaps this phenomenon should have a name, maybe "hyphen decay". A noun phrase becomes so current that starts being treated as a single word and is granted a hyphen in recognition of its new status. If the word becomes popular enough, even the hyphen is dropped and the words fuse.
"Bell boy" becomes "bell-boy", then "bellboy". Ditto for hundreds of other words from "type writer" to "lap top".
Orangutan is unusual in that the words originated in a non-Western language (albeit one that used Latin characters) and the hyphen was apparently added in the process of importing the word into English.
The correct way when I was growing up in Singapore is that it's an orang utan (two words) because 'orang' means Man in Malay (one of our national languages) and 'utan' means Forest. So literally - Man of the Forest. The pronunciation is oh-rung u-tahn, not oh-rang-a-tan which remains really strange to hear. The hyphenation probably came about when someone wanted to correct it without wanting to separate the two words.
Perhaps to prevent reading it as o-ran-gu-tan instead of o-rang-u-tan.