Correct spelling


Correct spelling, explanation: briefcase is the correct form as this is a compound noun brief+ case. Brief here means paper as in the 16th century meaning short writing. The word comes from Latin breve (a noun from an adjective meaning short). Therefore the correct form is briefcase as the spelling is closer to the original Latin word; not breifcase.

Definition of briefcase:
noun, a kind of portable case to hold documents and papers, usually a type of bag, typically used by men
Jack forgot his briefcase, so we don’t have the most important documents.
– How much is this briefcase? – It was $30.

Incorrect spelling


Incorrect spelling, explanation: This spelling is incorrect, despite the fact that for some breifcase may seem more intuitive based on the pronunciation. This is however a mistake because brief in briefcase stands for a piece of paper coming from Latin breve, meaning the same thing. The spelling in English changed but generally, it is closer to the original, therefore briefcase is the correct form.