From eu ('well') and thumos ('spirit/soul/passion'). Euthumeo means to be in good spirits, to be cheerful and encouraged β an inward state of bright, confident courage.
Euthumeo appears three times in Acts, twice as Paul's encouraging command to terrified sailors during a storm (27:22, 25) and once as the command to the sick in James 5:13. Paul's 'Be of good cheer' (euthumeo) in the midst of a life-threatening storm is remarkable β it is not denial of circumstances but confidence in divine promise. He had received God's word that all aboard would be saved. Christian cheerfulness is not pretending the storm isn't real; it is anchoring the soul in a promise greater than the storm. James's use shows that joyful singing in suffering is the appropriate spiritual response for those who trust God's sovereign care.