There are various terms we could choose, Diana, that may be better that my pet term, such as Unspecified, Unrecorded, Mystery, Skip, etc. I do feel, however, that we should not use Unknown, if only because of GEDCOM uploads that use that term; we want those Unknowns to be captured by the error report, so we need a different term.
Whatever term we choose will probably be somewhat inexact, Ellen, but it will differentiate the data field from the current empty/Unknown choice. That is the main goal of this discussion, to decide if we need or want to create a gender subset that isn't error checked and if any benefits justify any costs.
The term itself is mainly to tell the error report to skip the field, but it should have some relevant meaning also to avoid excessive confusion.