"I see someone every day" - meaning you see someone every day. "I see someone every other day" - meaning you see someone one day, not the next, then the day after, but not the next and so on.

What is "I see someone every two days"?

I am sure it means you see someone, have a 2 day break, see them again, then have another 2 day break.

But then I thought, every two days could be one day in between, because every day has no days in between, and 2 comes after 1.

Lucy washes her hair every other day.

Hi,
Is it right to interpret "every other day" in the above as "every two days?" Thanks.

every other day- is perfect.
every two days - also works well.

http://forum.wordreference.com/showthread.php?t=1580342