sand (n.) Look up sand at Dictionary.com
Old English sand, from Proto-Germanic *sandam (cognates: Old Norse sandr, Old Frisian sond, Middle Dutch sant, Dutch zand, German Sand), from PIE *bhs-amadho- (cognates: Greek psammos "sand;" Latin sabulum "coarse sand," source of Italian sabbia, French sable), suffixed form of root *bhes- "to rub."

Historically, the line between sand and gravel cannot be distinctly drawn. Used figuratively in Old English in reference to innumerability and instability. General Germanic, but not attested in Gothic, which used in this sense malma, related to Old High German melm "dust," the first element of the Swedish city name Malmö (the second element meaning "island"), and to Latin molere "to grind." Metaphoric for "innumerability" since Old English. Sand dollar, type of flat sea-urchin, so called from 1884, so called for its shape; sand dune attested from 1830.
sand (v.) Look up sand at Dictionary.com
late 14c., "to sprinkle with sand," from sand (n.); from 1620s as "to bury or fill in with sand." Meaning "to grind or polish with sand" is from 1858. Related: Sanded; sanding.