"LOGIN" or "LOG-IN" or "LOG IN" ?

Two administrators had a question that they wanted to resolve. They were attempting to "future-proof" a policy document that they were composing.  The document contained instructions on how to access a particular part of a website.  Their dilemma was this; should the command be written as "login", "log-in" or "log in"?  The solution that they arrived at was to Google all three variant spellings, and the version with the most hits was the one they were going to use.  I have replicated their search, with the following results:

      "Log in"   5,330,000,000 hits
      "Log-in"   5,300,000,000 hits
      "Login"    1,600,000,000 hits
 
I do not know whether or not they consulted a dictionary as part of this process.  As a reference librarian, this would be my first “go to” source for this type of question.  The Oxford English Dictionary Online provides an unambiguous answer:
 
     "Log-in" is defined as a noun; "Computing.  The action or act of logging in...esp. designating a procedure which is carried out every time a user logs in."
      "Log in" is defined as a verb; "... to log in or on (intransitive), to open one's on-line access to a computer, esp. a database or other time-shared system, from a terminal..."
 
A search for "login" refers one back to the two variants above, suggesting that "login" is unacceptable to the OED Online. Merriam-Webster Online matches and tracks the findings of the OED.  So, the "crowd sourcing" solution seems to reflect what the dictionaries are telling us, with "login" coming in third place in the popularity race.

But one has to acknowledge that a dictionary entry is only a “fossilized” version of the definition of a word. Dictionary editors will only add a word to their roster when it has been in common use for some time, and only if they deem the word to be worthy of inclusion. A recent article by Padraic Flanaghan in the Daily Telegraph (London) highlights the problem dictionary editors have when updating dictionaries. The sheer volume of material available on the web means that dictionary compilers have to trawl through many more sources than they once did. Flanaghan reports that the current print issue of the OED is already twenty years overdue, and will probably be the last published in print.

So, if a dictionary is only a reflection of common usage, then maybe “crowd sourcing” is the solution to writing new dictionary entries. It might certainly prove to be faster!

Flanaghan, P. (2014, April 21). Too big to print: OED may go online only due to information overload. Daily Telegraph (London), p.7.