secrecy: the cover under which something is done so that nobody notices it happening
This word names concealment itself. In the Bible it turns up almost only inside a set phrase that uses it to describe how an act was carried out: under cover, unnoticed. Behind it stands a verb for wrapping or muffling something up (לוּט), so the picture is of an act that has been veiled, not of a place a person hides in (which is what סֵתֶר names).
Its one appearance in this spelling is Judges 4:21, where Jael takes a tent peg and a mallet and comes to the sleeping Sisera in secrecy. Translators have divided over that line for centuries. Older English has her go "softly", newer versions have her come "stealthily", and the two great early Greek manuscripts of Judges disagree with each other in exactly the same way, one reading "in secret" and the other "quietly". The reason is simple: an approach that is covered is also an approach that is silent, so the word sits right where hiding and hushing overlap.
A separate small word that plainly means "gently, slowly" (אַט) looks and sounds much like this one, and most scholars now treat the two as different words that happen to resemble each other. That is why "softly" stays a live option at Judges 4:21 even though this word itself is about being hidden rather than being quiet.
Whether the word at Judges 4:21 says that Jael approached Sisera stealthily or only quietly.
- majorityStealthily, under cover and with intent: the word belongs to the fixed phrase for acting in secret, whose other occurrences (Ruth 3:7; 1 Samuel 18:22; 24:4) all concern concealment.; Codex Alexandrinus, Judges 4:21 (ἐν κρυφῇ); Boling, Judges (Anchor Bible 6A, 1975); Block, Judges, Ruth (NAC 6, 1999); Webb, The Book of Judges (NICOT, 2012)
- minorityQuietly, softly: the word describes a noiseless approach to a sleeping man rather than a concealed one, taking it with the small word meaning gently or slowly.; Codex Vaticanus, Judges 4:21 (ἡσυχῇ); King James Version, Judges 4:21 (went softly); Gesenius, Hebrew and Chaldee Lexicon to the Old Testament Scriptures, s.v. לאט