5447. phusikós
Lexical Summary
phusikós: instinct

Original Word: φυσικός
Part of Speech: Adverb
Transliteration: phusikós
Pronunciation: foo-see-KOS
Phonetic Spelling: (foo-see-koce')
KJV: naturally
NASB: instinct
Word Origin: [adverb from G5446 (φυσικός - natural)]

1. "physically"
2. (by implication) instinctively

Strong's Exhaustive Concordance
naturally.

Adverb from phusikos; "physically", i.e. (by implication) instinctively -- naturally.

see GREEK phusikos

HELPS Word-studies

Cognate: 5447 physikṓs (an adverb) – properly, naturally, i.e. acting by mere instinct (used only in Jude 1:10). See 5449 (physis).

NAS Exhaustive Concordance
Word Origin
adverb from phusikos
Definition
naturally, by nature
NASB Translation
instinct (1).

Thayer's Greek Lexicon
STRONGS NT 5447: φυσικῶς

φυσικῶς, adverb, in a natural manner, by nature, under the guidance of nature: by the aid of the bodily senses, Jude 1:10. ((Aristotle, Philo, others.))

Topical Lexicon
Definition and Core Idea

The term rendered “naturally” in Jude 1:10 describes behavior arising from unregenerate instinct rather than from reason enlightened by God’s Word or the renewing influence of the Holy Spirit. It highlights the sphere of fallen nature—automatic, self-serving impulses that characterize those untouched by grace.

Biblical Context: Jude’s Warning

Jude 1:10 employs the adverb to expose false teachers who “blaspheme anything they do not understand, and what they do understand by instinct, like irrational animals—by these things they are destroyed”. Jude sets their instinct-driven conduct in sharp contrast to the faith “once for all entrusted to the saints” (Jude 1:3). Their reliance on mere appetite reveals why their influence is destructive: it is rooted in the same self-willed rebellion that marked the angels who abandoned their proper domain (Jude 1:6) and the people of Sodom and Gomorrah who pursued “sexual immorality and perversion” (Jude 1:7).

Contrast Between Natural Instinct and Spiritual Discernment

New Testament writers repeatedly distinguish life governed by fallen nature from life governed by the Spirit:
• “The natural man does not accept the things that come from the Spirit of God” (1 Corinthians 2:14).
• “The mind of the flesh is death, but the mind of the Spirit is life and peace” (Romans 8:6).
• “There are men driven by the flesh who despise authority” (2 Peter 2:10, cf. 2 Peter 2:12–13).

Though these passages use different Greek expressions, they illuminate Jude’s single occurrence by portraying the same moral fault line—instinct versus revelation.

Relation to the Fallen Nature

After the fall, humanity’s natural impulses became disordered. What was created “very good” (Genesis 1:31) now bears the corruption traced to Adam (Romans 5:12). Consequently, instinct alone cannot be trusted. Unless restrained by common grace or transformed by saving grace, it gravitates toward self-exaltation, sensual indulgence, and contempt for divine authority, precisely the traits Jude condemns.

Historical and Cultural Background

In the first-century Greco-Roman milieu, appeals to “nature” could be positive or negative. Stoic philosophers praised living according to nature, yet Scripture insists that true wisdom begins with the fear of the Lord (Proverbs 9:10) and is fully revealed in Christ (Colossians 2:3). Jude therefore challenges a cultural assumption: what feels natural is not necessarily what honors God.

Theological Implications

1. Anthropology: Humanity apart from Christ is not morally neutral; instinctive drives are bent toward rebellion (Ephesians 2:3).
2. Hamartiology: Sin is deeper than isolated acts; it is a principle that permeates the natural man (Romans 7:18).
3. Soteriology: Regeneration provides a new principle of life, enabling believers to “put to death the deeds of the body” (Romans 8:13) and to “walk by the Spirit” (Galatians 5:16).

Practical Ministry Application

• Preaching and Teaching: Underscore that sincerity or “following one’s heart” is not a safe guide; only Scripture, illuminated by the Spirit, guards from deception.
• Counseling and Discipleship: Help believers identify impulses that emerge from old patterns. Encourage practices—prayer, fellowship, Scripture meditation—that retrain desires toward holiness.
• Church Leadership: Be alert to teachers who appeal to felt needs or sensual freedom, yet dismiss doctrinal truth. Jude’s example calls for swift, compassionate, but firm corrective action.

Related Scriptures

Genesis 6:5; Jeremiah 17:9; Matthew 15:19; Romans 1:24–28; Romans 8:5–9; 1 Corinthians 2:14; Galatians 5:19–25; Ephesians 2:1–3; 2 Peter 2:12–14; Jude 1:8–19.

Forms and Transliterations
φυσικως φυσικώς φυσικῶς phusikos phusikōs physikos physikôs physikōs physikō̂s
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Englishman's Concordance
Jude 1:10 Adv
GRK: ὅσα δὲ φυσικῶς ὡς τὰ
NAS: they know by instinct, like
KJV: what they know naturally, as brute
INT: whatever things moreover naturally as the

Strong's Greek 5447
1 Occurrence


φυσικῶς — 1 Occ.

5446
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