Multiwired small coil
It sounds like you're talking about a coil wound with Litz wire. Litz wire uses multiple individual conductors instead of a single fat conductor in order to reduce the negative consequences of skin effect and proximity effect (where high frequency current flows mostly in the outer skin of the conductor, thus increasing the effective resistance and thus power loss). Image from myself:



It's mostly used for frequencies above audio but below a couple MHz, for example, for induction cooker coils and high frequency switching supply transformers.