From Merriam-Webster:  Plangent adds power to our poetry and prose: the pounding of waves, the beat of wings, the tolling of a bell, the throbbing of the human heart, a lover’s knocking at the door – all have been described as plangent. The word plangent traces back to the Latin verb plangere, which has two meanings. The first of those meanings, “to strike or beat,” was sometimes used by Latin speakers in reference to striking one’s breast in grief. This, in turn, led to the verb’s second meaning: “to lament.” The sense division carried over to the Latin adjective plangens and then into English, giving us the two distinct meanings of “plangent”: “pounding” and “expressive of melancholy.”