συγκοινωνέωsynkoinōnéō

to share in company with, i.e. co-participate in

Greek (New Testament) · G4790

Meanings

to have fellowship with or in (in classical Greek, with genitive of thing, dative of person): with dative of thing, Ephesians 5:11, Revelation 18:4; id. with genitive of person, Philippians 4:14.

Same root

σύνsýn · G4862with or together (but much closer than G3326 (μετά) or G3844 (παρά)), i.e. by association, companionship, process, resemblance, possession, instrumentality, addition, etc.
κοινωνέωkoinōnéō · G2841to share with others (objectively or subjectively)

Where it appears

Appears 3 times in the Bible.

Ephesians 5:11 Take no part in the worthless deeds of evil and darkness; instead, expose them.
Philippians 4:14 Even so, you have done well to share with me in my present difficulty.
Revelation 18:4 Then I heard another voice calling from heaven, “Come away from her, my people. Do not take part in her sins, or you will be punished with her.

Source: G. Abbott-Smith, A Manual Greek Lexicon of the New Testament (1922), public domain.