Few distinctions in English are as confusing and subtle as the difference between everyday and every day. Not only is it tricky for new learners but native English speakers are also likely to use "everyday" incorrectly.
Everyday as a single word is an adjective (a descriptor) — it means ordinary or commonplace. Every day — two different words — means "each day."
Here are some examples for using every day and everyday correctly:
- Lisa takes her dog out for a walk every day.
- It is important to floss every day.
- It is not every day that my company gives me an award for excellent work.
- You may think that a toll booth attendant is inconsequential but imagine how many people she can affect just by her demeanor during everyday interactions.
- Jack didn't take very good care of his everyday clothes but his church clothes for Sunday were always dry-cleaned.
- In everyday use, people tend to say "weight" when they really mean "mass."
- I believe it’s more important to be kind in our everyday actions than to pray every day.
Even after understanding this difference between the two words, one is likely to falter when using "everyday occurrence". After all, if it's something that occurs daily shouldn't you say "every day occurrence"? The answer is No.
An "everyday occurrence" — somewhat confusingly — does not necessarily mean it occurs every day. It only means means it's an ordinary, commonplace occurrence. It is not something unusual. Remember that everyday is an adjective. So it describes an attribute (ordinariness) of the occurrence.
If something occurs daily, you can say it "occurs every day" or that it is a daily occurrence. "Every day occurrence" is wrong usage. Since "every day" is an adverb, it cannot be used as an adjective to describe the occurrence.
Another common usage of "everyday" is the phrase "everyday lives". Synonyms for that are "day-to-day lives", "daily lives" or "routine", and it refers to how people typically think and act in life on most days. Note that "every day life" is incorrect.