Aim for precision: why "principle aim" misses the mark

What kind of error is it?

Word choice error

Why do people make this mistake?

People often make this error because the words "principle" and "principal" are homophones—they sound the same but have different meanings and spellings. In this context, "principal aim" is the correct collocation, meaning the primary or main aim of something.

What is correct?

The correct term is "principal aim". "Principal" is an adjective that means most important or main, which fits the context of aiming or focusing on the primary objective.