συναγωνίζομαιsynagōnízomai

to strive together with, to help (properly, of sharing in a contest): with dative of person et rei, Romans 15:30.

Greek (New Testament) · G4865

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.
ἀγωνίζομαιagōnízomai · G75to struggle, literally (to compete for a prize), figuratively (to contend with an adversary), or genitive case (to endeavor to accomplish something)

Where it appears

Appears 1 times in the Bible.

Romans 15:30 Dear brothers and sisters, I urge you in the name of our Lord Jesus Christ to join in my struggle by praying to God for me. Do this because of your love for me, given to you by the Holy Spirit.

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