How should I translate the English word "smoothie" to Esperanto? I saw that there is an Esperanto Wikipedia article called "Smuzio" which links to the English article about smoothies. But this word seems to be missing in PIV, Reta Vortaro and the dictionary of Lernu.net. Should I use this word or should I use another word to refer to this concept?
I've never heard of a smuzio.
Alternatives include: fruktpulpaĵo, fruktlaktaĵo, miksita frukta trinkaĵo, Fruktkirlaĵo
Nobody spoke out in favor of smuzio in this discussion about the topic:
Smuzio is fine for the specific use of trinkaĵo farita (el fruktoj kajaŭ legomoj) per miksilo. It is just an Esperanto respelling of "smoothie", which is very international.
The clunky alternatives, fruktkirlaĵo, fruktlaktaĵo, etc, get across the idea of "fruit thing", but could also refer to a lot of different things which aren't smoothies. If I couldn't use smuzio or didn't like it for some reason I would say miksila trinkaĵo.
If you go to the web version of the article "Smoothie" on English Wikipedia, and run your mouse pointer over the language side bar on the left, you will find that nearly every other Wikipedia uses Smoothie as the headword, or a close transliteration. Clicking through, you will find that this is not an accident: most of the languages use smoothie without even respelling it. Thus, by Rule 15, smoothie is easily a candidate for induction into Esperanto, and you could just write things like Mi ĝuis smoothie sur la plaĝo in most contexts—that's what people do in their native languages.
The next question: is smuzio a good fit for Esperanto—is it ugly or corny or too easy to confuse with another word? I don't think so—it resembles muzeo but not closely, and the only words in Wells's dictionary that start with sm are smeraldo, smilako, smirgo, smokingo and smuto. It is distinctive and easy to say and remember, and can't be mistaken for a compound. Native English-speakers may recognize it with difficulty (as they think of th and z as completely different sounds, and the accent is in the wrong place)—that's the only objection I can think of straight away.
The next question: is there an obviously better compound word to use instead? e.g. najleto for "thumbtack" etc? In this case, there is no obvious one. A smoothie can contain fruit, but not always. It can contain vegetables, but not always. It is usually cold and sweet, but not always. What smoothies have in common is that they are drinks, and they are made in (more or less) a one-step process with a blender. So if you prefer a Bona Lingvo style, the most generally applicable translation is probably miksiltrinkaĵo. (I think fruktkirlaĵo is just okay—it is hard to pronounce, and the first time I saw it, I vaguely assumed it to be some sort of fruit salad.) But smuzio is international and gives you a short, specific word for a simple, specific idea. So it's fine.