mouth half-open or half-opened

[Bushwhacker]

Which is better said:

mouth half-open or half-opened?

Thank You

[riquecohen]

Half-open.

[Bushwhacker]

Half-open.

Thank You very much for your kind answer. Can You explain me the reason, please?

[Bushwhacker]

Half-open.

Thank You very much for your kind answer. Can You explain the reason, please?

[BobK]

Thank You very much for your kind answer. Can You explain the reason, please?

It's 'open' as in an 'open door'; similarly, you would say 'half-open door' - which refers to the state of the door in relation to the doorway, rather than to the action of someone opening it.

b