Kruptos describes what is kept out of view, whether private actions, concealed matters, or the inward person.

The occurrences consistently describe something out of public view: concealed matters that may become known, actions done privately rather than openly, and the inward person or identity of the heart. The same basic usage is applied to darkness, thoughts, charitable giving and prayer, public teaching, and inward character.

1. Out of view or kept private · dominant

   The neuter forms describe matters not openly known: in 1 Corinthians 4:5 the APB renders the clause “the hidden things of the darkness,” which the Lord will illuminate, while in Luke 8:17 it renders what is hidden as becoming clear. In Matthew 6:4 the dative form occurs where charity is done “in secret,” and in 1 Peter 3:4 the masculine singular form identifies “the hidden person of the heart.”

   1 Corinthians 4:5Luke 8:17Matthew 6:4John 7:10John 18:201 Peter 3:4

In the Anselm Project Bible: The APB variously uses “hidden,” “in secret,” “concealed,” and “private” across these verses. Those variations show the verse-level settings rather than separate lexical meanings.