A sweet smell, fragrance, or pleasant aroma. Used metaphorically for the 'aroma of Christ' — the spiritual fragrance that believers carry. In the ancient world, a victorious general's procession included incense bearers; Paul uses this image for the church's witness spreading like fragrance through the world.
Euodia transforms evangelism from argument into aroma. Paul says believers are 'the pleasing aroma of Christ' (2 Corinthians 2:15) — but this fragrance has a dual effect: to those being saved, it smells like life; to those perishing, like death. The gospel is not neutral. Christ's sacrifice was a 'fragrant offering' to God (Ephesians 5:2), and our lives, when lived in self-giving love, continue that fragrance in the world.