waste	Garbage, rubbish or trash.
water current	Generally, a horizontal movement of water. Currents may be classified as tidal and nontidal. Tidal currents are caused by gravitational interactions between the Sun, Moon, and Earth and are part of the same general movement of the sea that is manifested in the vertical rise and fall, called tide.
wave	Energy disturbance moving through or over a surface, resulting in oscillations in the properties of the medium.
wave crest	The highest portion of a wave, or that portion above the level of still water.
wave length	The distance between one point on a wave and the same point on the next wave (e.g., one full crest and its accompanying trough).
WHO	Acronym for World Health Organisation.