The Collaborative International Dictionary of English v.0.48:
Plangent \Plan"gent\, a. [L. plangens, -entis, fr. plangere to beat. See Plaint.] Beating; dashing, as a wave. [R.] "The plangent wave." --H. Taylor. [1913 Webster] PlaniWordNet (r) 3.0 (2006):
plangent adj 1: loud and resounding; "plangent bells"; "the plangent minority"