Greek word · G3024

λήθη

lēthē

forgetfulness

Forgetfulness, oblivion, losing something from memory. With lambanō, "to take forgetfulness," it is an established Greek idiom meaning "to forget" or "to let slip from mind."

Appears once in the Greek New Testament. · Updated October 31, 2026

What it means

λήθη, -ης, ἡ

(λήθω = λανθάνω) [in LXX: Leviticus 5:15 (מַעַל), Wisdom of Solomon 16:11, Sirach 14:7, al. ;]

forgetfulness: λ. λαβεῖν (on the phrase, see Mayor, in l): 2 Peter 1:9.†

(AS)

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

In depth

From the study of 2 Peter 1:9

Range of meaning: Forgetfulness, oblivion, losing something from memory. With lambanō, "to take forgetfulness," it is an established Greek idiom meaning "to forget" or "to let slip from mind."
Against the English: KJV and BSB: "hath forgotten / having forgotten." YLT: "having become forgetful." English "forget" can sound like an innocent slip of memory. In ancient moral writing, Jewish and Greek alike, forgetting what defines you was a moral failure.
How it drifted: Modern English treats forgetting mostly as a mental accident. Biblical and Hellenistic ethics treated memory as something you practise and are responsible for.
Used elsewhere in the period: The idiom lēthēn lambanein appears in Hellenistic Greek authors, Josephus among them. It is a 'This is the only New Testament use of the noun lēthē. Behind it lies the Old Testament warning, "Beware lest you forget the LORD" (Deut 8:11–14; 6:12), where forgetting means drifting from God in practice, not a lapse of memory.

Where it appears

2 Peter · 1

2 Peter 1:9 λήθην forgetfulness

But whoever lacks these traits is nearsighted to the point of blindness, having forgotten that he has been cleansed from his past sins.

Here: Forgetfulness. Related to the river Lēthē of Greek myth, which wiped away memory. Here it means letting something essential slip out of mind.

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