From an email:

“I am editing a book written by my mother-in-law…what is the difference between Good night and goodnight?”

Good question, and it’s one that stumps many a Reluctant Writer.

It’s two words when you mean:

Good night, as in, “Have a good night.”

It’s one word when you mean:

Goodnight, the wish: “Goodnight, don’t let the Martians bite.”

It can be challenging to distinguish between word pairs that are separated by nothing more than a tap on the space bar…and a grammar lesson from years past.

In this instance, it really does come down to grammar: You could be dealing with a pronoun, adjective, noun, or adverb. It depends on the word pair in question, and how well you understand the underlying grammatical principle.

There’s no basic rule to follow, and reading your work aloud probably won’t help.

In short, it’s frustrating, which is why so many kind-hearted grammarians put together lists like these.

Minus the grammar lesson, I’ve addressed a few commonly confused word pairs below.

Anymore — You don’t bring me flowers anymore.
Any more — I don’t want any more food today.

Every day – I take the bus to work every day of the week.
Everyday – Missing the bus is an everyday occurrence.

Everyone – Everyone cried at the funeral.
Every one – I wish every one at work would join the softball league.

Oftentimes
Often times
Trick question! It’s only oftentimes.

What to do?
The easy fix is to type the word pair into Google and add on, “one word or two.”