What's the correct way to write "foodservice"?

The Cambridge Dictionary writes it in two words while the Wiktionary writes it in one. Wikipedia mostly writes it in one word, but sometimes in two.

Should it be written "food service" or "foodservice"? Or is there a special rule over this?

ps: I'd link to the Wikipedia article, but I don't have enough reputation. Sorry about that.

Solution 1:

"Food service" is attested by Google Ngram Viewer starting around 1900, and is still on the rise. "Foodservice" is first attested around 1970 and is now used about 1/5 of the time. ("Food-service" is not used.) So "foodservice" is still going to look strange to most people but is gaining acceptance.

Solution 2:

The OED doesn't recognize foodservice at all, and nor do I.

Solution 3:

Further Choster's reply, and somewhat counter to the other answers, in the United States it appears "foodservice" is an (if not the) accepted and expected industry term. In terms of writing correctly for this industry in the U.S., based on the number of industry groups and industry publications that use "foodservice" in their name, it would be incorrect to assume that "foodservice" looks strange "to most people," and conclude it is strictly an alternative/erroneous spelling. (Though I don't doubt that is how it came about). I don't think "food service" is wrong, but for U.S. industry usage I'm going ahead with "foodservice."

Examples: Foodservice Director dot com; Foodservice Consultants Society International; Foodservice News dot net; Foodservice Monthly dot com (the Newsmagazine Foodservice Professionals Rely On).

These are just a few from the first page of my Google search on "foodservice or food service."

Solution 4:

Foodservice usually refers to the food service industry: businesses and people engaged in preparing meals for consumption outside the home, chiefly restaurants and institutional cafeterias and their suppliers and distributors. This may be an Americanism, as I have seen the term catering industry used in British publications; "catering" is not used so broadly in the U.S.

When two short words are used so commonly together to refer to a single concept, it is not uncommon they will merge. Airlines began as air lines (a term borrowed from railways), and indeed we still have Delta Air Lines and United Air Lines. I submit healthcare and webhosting for more contemporary examples.

I would expect to see "food service" in more conservative usage, and where I want to make a direct reference to the service of food: "The in-flight entertainment was mediocre, but the food service was good" (that is, the food was good or the manner in which it was served was good, not the corporate supplier of the food).