Monos (G3289 variant; primary G3441) means alone or only — used of God ('God alone,' 'the only God'), of Jesus ('only begotten'), and of humans in isolation. This word undergirds the great doxologies: 'to the only wise God' (Rom 16:27), 'the only Sovereign, King of kings' (1 Tim 6:15). Monos applied to God is a theological statement about His uniqueness — He is in a class by Himself, with no rivals, no peers, no equals.
The monos of God is the foundation of biblical monotheism and worship. When the Shema declares 'the LORD our God, the LORD is one (echad)' — the corresponding Greek concept is monos: God alone. Jesus affirmed this: 'I and the Father are one' (John 10:30) — and His high priestly prayer centers on knowing the 'only true God' (John 17:3, ton monon alethinon theon). Every idol is a lie against the monos of God. The exclusivity of God's being demands the exclusivity of our worship — He alone is God; He alone is worthy.