W18 may refer to:
W-18 (drug), a designer drug British NVC community W18, a woodland community in the British National Vegetation Classification system Hansa-Brandenburg W.18, a German flying boat fighter , a tug of the Royal Navy Malgana language Mercedes-Benz W18, an automobile Snub dodecahedron Suburban Airport, in Anne Arundel County, Maryland, United States W18 engine, an eighteen-cylinder engine Water-jugs-in-stand (hieroglyph), an Egyptian hieroglyph