Koniao describes something made white on the outside, in images of a wall and graves.

The two verses use the term for an outward white appearance: a whitewashed wall in Acts 23:3 and graves that appear beautiful externally in Matthew 23:27.

1. Made white outwardly · dominant

   Both occurrences are perfect passive participles. In Acts 23:3, the vocative singular form addresses a “wall having been whitewashed” in Paul's rebuke; in Matthew 23:27, the dative plural form modifies graves that outwardly appear beautiful while their interiors are described otherwise.

   Acts 23:3Matthew 23:27

In the Anselm Project Bible: The APB presents the image as “wall having been whitewashed” in Acts 23:3 and “whitewashed graves” in Matthew 23:27. These phrases occur in a translation.