Is It Someday or Some Day?

Someday means “at an indefinite time in the future.” Some day refers to one day that is perhaps unknown or unspecified.

Is some day one word or two?

“Someday” refers to an unspecified time in the future, as in “Someday my prince will come.” As two words, “some day” refers to an unspecified but specific day: The interview will be scheduled for a particular but unspecified day the following week. “Someday” is incorrect in that context.

How do you use some day?

If you're referring to a future event that will occur on an unspecified, single day, then you would use the phrase some day. If you're referring to an occasion, or series of events at a distant, indefinite time, then using the word someday is correct.