Asphalos describes keeping someone under secure control or knowing a stated fact with certainty.

The term most often qualifies actions of custody or removal carried out under secure control; in a separate use, it qualifies Israel's knowledge as certain concerning what God has made Jesus. The three occurrences therefore show security in handling people and certainty in knowing a declaration.

1. Secure custody or removal · dominant

   In Acts 16:23, the adverb qualifies the jailer's commanded guarding of prisoners after they are thrown into prison; the APB renders the clause "to guard them securely." In Mark 14:44, it qualifies the instruction to seize the identified man and take him away; the APB renders "lead him away securely."

   Acts 16:23Mark 14:44
2. Certainty in knowing · occasional

   In Acts 2:36, the adverb qualifies the charge that all Israel know the stated conclusion about Jesus; the APB renders the clause "know for certain" that God has made him Lord and Christ.

   Acts 2:36

In the Anselm Project Bible: The APB presents the custody contexts with "securely" and the knowledge context with "for certain." These renderings confirm the clauses' overall force rather than establish a separate English equivalent in each verse.