prumna denotes the rear part of a ship, where anchors are cast or which can be damaged in a grounding.

The attested passages use the term for the rear section of a ship: it is the place from which anchors are thrown, where someone sleeps, and the part damaged when a ship runs aground.

1. The rear section of a ship · dominant

   In Acts 27:29, the genitive singular form occurs in the clause about throwing four anchors from that part of the vessel. In Acts 27:41, the nominative singular form contrasts with the bow as the ship's rear is broken up; Mark 4:38 locates someone there, with the dative singular form.

   Acts 27:29Acts 27:41Mark 4:38

In the Anselm Project Bible: The APB presents the term as "stern" in all three verses, in contexts of anchoring, sleeping, and ship damage. This repeated wording confirms the verse-level setting rather than a separate nuance.