Something that spoils an otherwise good thing. Indeed, even a tiny impurity like a dead fly can ruin an exorbitant scent, similarly, a little misjudgment can destroy the notoriety of an astute man. “Dead flies cause the ointment of the apothecary to send forth a stinking savor: so doth a little folly him that is in reputation for wisdom and honor.” Ecclesiastes 10:1 KJV