open-necked
US /ˌoʊ.pənˈnekt/
UK /ˌoʊ.pənˈnekt/

1.
a collo aperto, scollato
having a collar that is not fastened at the neck, or no collar at all
:
•
He wore an open-necked shirt to the casual dinner.
Indossava una camicia a collo aperto per la cena informale.
•
The dress had an elegant open-necked design.
L'abito aveva un elegante design a collo aperto.