login

Many who are neither professionals in the computer field nor amateur tech enthusiasts condemn the use of the solid form login as a verb, and with good reason. It doesn’t behave like a normal verb. You cannot say you have loginned, and you are never in the process of loginning. Moreover, you cannot even ask someone to login you; you must ask that person to log you in. Clearly, it is the two-word phrase log in that functions fully as an English verb, not the solid form. Normally, we would expect the verb phrase log in and the noun login to behave in the same way as similar pairs: blow out/blowout, crack down/crackdown, hang up/hangup, splash down/splashdown, turn off/turnoff, where the two-word phrase is a verb and the one-word form is a noun. And yet, this gluing together of terms like login, logon, backup, and setup as verbs is common, especially in writing about computers. Not for everyone, though; some well-known software companies, for example, carefully maintain the distinction in their programs and documentation. The wisest course is to find out what the standard is among those for whom you’re writing, and follow it.