1. Any disagreeable or undesired sound.
2. A class of sounds, generally of a random nature, which do not exhibit clearly defined frequency components.
Reference: Icharge currentIntensity.EIlluminanceEnergy.CContrastCelsius (previously Centigrade)Capacitance.
Please note that this is the term as it stands in the original IALAInternational Association of Marine Aids to Navigation and Lighthouse Authorities - AISM Dictionary edition (1970-1989)