The Greek adjective euthymos (εὔθυμος) means cheerful, of good cheer, in good spirits, encouraged. Combining eu (good, well) and thymos (spirit, passion, mind), it describes a state of positive morale and courage in adverse circumstances. Its adverbial form euthumōs appears in Acts 24:10. The adjective appears in Acts 27:36.
Acts 27 is perhaps the NT's greatest storm narrative, and Paul is its calm center. As hurricane Euroclydon rages and all hope of survival is abandoned (v.20), Paul stands and urges the terrified crew: "Take heart" — euthumeō. He has received God's promise of safety for all aboard, and he declares it with authority. When dawn comes and they prepare to run ashore, the crew "took courage" (euthumoi) and ate. This is not naive optimism — it is faith-grounded courage in the teeth of catastrophe. The cheerfulness of the people of God is not circumstantial; it is anchored in divine promise.