Greek word · G804

ἀσφαλής

asphalēs

secure

From a- ('not') and sphallō ('trip, make fall'): not liable to fall, safe, secure; certain, reliable (of knowledge or facts).

Appears 5 times in 5 verses of the Greek New Testament. · Updated October 23, 2026

What it means

ἀσφαλής, -ές

(ἀ- neg., σφάλλω, to trip up), [in LXX for אָשַׁר pu., etc. ;]

certain, secure, safe: Acts 21:34 22:30 25:26, Philippians 3:1, Hebrews 6:19 (MM, see word).†

(AS)

From G. Abbott-Smith, A Manual Greek Lexicon of the New Testament (1922), via STEPBible.org (CC BY 4.0).

Range of meaning: From a- ('not') and sphallō ('trip, make fall'): not liable to fall, safe, secure; certain, reliable (of knowledge or facts).
Against the English: 'Sure' (KJV) leans toward certainty of knowledge; 'secure' (BSB) toward physical safety. The Greek covers both, but with an anchor the physical picture leads: it does not drag or slip.
Used elsewhere in the period: Acts 21:34; 22:30; 25:26 'the certain facts' (to asphales); Phil 3:1 'it is safe for you'. The related noun asphaleia appears in Luke 1:4: 'that you may know the certainty'.

Range of meaning: Firm, steady, safe (literally 'not liable to slip'). By extension it means certain, reliable, trustworthy. Used as a noun, τὸ ἀσφαλές means 'the certain facts' or 'the reliable truth' about a matter.
Against the English: The KJV and YLT say 'the certainty', the BSB 'the real reason' and the WEB 'the truth'. All are accurate. But 'truth' can sound abstract or philosophical, when the word means facts solid enough to act on and put in an official report.
Used elsewhere in the period: It is common in Greek historians and in administrative language for secure and verified information. Luke uses this word group on purpose. His Gospel opens with the aim that Theophilus may know 'the certainty' (ἀσφάλεια, Luke 1:4). In Acts 21:34 the tribune cannot learn τὸ ἀσφαλές because of the uproar. In 25:26 Festus has 'nothing ἀσφαλές' to write to the emperor about Paul.

Range of meaning: Literally 'not liable to trip or fall' (a- 'not' + sphallō 'to trip, cause to fall'). Hence 'firm, steady, safe, secure', and of information 'certain, reliable'.
Against the English: KJV and WEB 'safe'. BSB and NASB 'a safeguard'. YLT 'sure'. 'Safe' can sound passive ('a safe bet'). The Greek suggests firm footing that keeps them from falling.
Used elsewhere in the period: Acts 21:34; 22:30; 25:26 ('the certain facts'); Heb 6:19 (hope as an anchor 'sure and steadfast'). The related asphaleia means 'certainty' in Luke 1:4 and 'security' in Acts 5:23 and 1 Thess 5:3.

Acts · 3

Acts 21:34 ἀσφαλὲς facts

Some in the crowd were shouting one thing, and some another. And since the commander could not get at the truth because of the uproar, he ordered that Paul be brought into the barracks.
Acts 22:30 ἀσφαλές, for certain

The next day the commander, wanting to learn the real reason Paul was accused by the Jews, released him and ordered the chief priests and the whole Sanhedrin to assemble. Then he brought Paul down and had him stand before them.

Here: 'The solid facts', information he can safely act on and report. The commander already failed to get these from the shouting crowd in 21:34.
Acts 25:26 ἀσφαλές definite

I have nothing definite to write to our sovereign about him. Therefore I have brought him before all of you, and especially before you, King Agrippa, so that after this inquiry I may have something to write.

Philippians · 1

Philippians 3:1 ἀσφαλές.¶ [is] safe.

Finally, my brothers, rejoice in the Lord. It is no trouble for me to write the same things to you again, and it is a safeguard for you.

Here: Literally 'not-tripping': something that keeps you from slipping. The repetition is protection, a steadying hold against the dangers named in the next verse.

Hebrews · 1

Hebrews 6:19 ἀσφαλῆ sure

We have this hope as an anchor for the soul, firm and secure. It enters the inner sanctuary behind the curtain,

Here: Literally 'not liable to trip or slip'. An anchor that will not drag across the seabed.

Word data: STEPBible.org (CC BY 4.0), main text only.