thea refers to a female deity, specifically Artemis in the verse where it occurs.

The attested use identifies Artemis as a female deity whose sacred place and majesty are described as threatened.

1. Female deity named Artemis · dominant

   In Acts 19:27, the genitive singular feminine form occurs in the clause about the sacred place of the great Artemis; the APB renders the phrase “the great goddess Artemis.”

   Acts 19:27

In the Anselm Project Bible: In Acts 19:27, the APB presents the term within “the great goddess Artemis.” It does not independently isolate the term's contribution.