1. Groan, moan refer to sounds indicating deep suffering. A groan is a brief, strong, deep-throated sound emitted involuntarily under pressure of pain or suffering: The wounded man groaned when they lifted him. A moan is a prolonged, more or less continuous, low, inarticulate sound indicative of suffering, either physical or mental: She was moaning after the operation. She did not weep, but moaned softly.