Origins
The word 'sand' descends from Old English 'sand' (sand, sandy ground, shore), from Proto-Germanic *samdaz (sand). The deeper etymology is uncertain but may connect to PIE *bhes- (to rub, to scrape), which would make sand etymologically 'the rubbed stuff' — material produced by grinding and abrasion. This derivation, if correct, is remarkably apt: sand is literally produced by the mechanical weathering of rock, the grinding of stone against stone over geological timescales.
The Germanic cognates are consistent in form and meaning: German 'Sand,' Dutch 'zand,' Swedish 'sand,' Danish 'sand,' Norwegian 'sand,' Old Norse 'sandr.' The word is remarkably stable across the Germanic languages, suggesting it was firmly established in Proto-Germanic vocabulary. The Old Norse form 'sandr' survives in the geological term 'sandur' (plural 'sandar'), meaning a glacial outwash plain — a flat expanse of sand and gravel deposited by meltwater streams flowing from a glacier.
A possible cognate outside Germanic is Greek 'psammos' or 'ammos' (sand), which appears in scientific terminology: 'psammophyte' (a sand-dwelling plant), 'psammite' (a type of sandstone), and 'ammonia' (named after the temple of Ammon in the Libyan desert, near deposits of ammonium chloride — the 'salt of the sand'). The phonological relationship between Germanic *samdaz and Greek psammos is plausible but not universally accepted by historical linguists.
Middle English
The compound words built on 'sand' reflect centuries of human experience with the material. 'Sandstone' (rock made of compressed sand) dates to the 16th century. 'Sandpaper' (paper coated with abrasive grit) dates to 1808. 'Quicksand' (sand that behaves like a liquid, that 'lives' and moves — from 'quick' in its original sense of 'alive') dates to the 14th century. 'Sandcastle' first appears in the 19th century. 'Sandbox' dates to the 17th century (originally a military term for a container of sand used to blot ink or extinguish fires).
The metaphorical uses of 'sand' in English are rich with philosophical weight. 'Sands of time' (from the hourglass, where flowing sand measures passing time) has been proverbial since the 16th century. 'Built on sand' (from the Biblical parable in Matthew 7:26 of the foolish man who built his house upon the sand) means founded on an unstable basis. 'To bury one's head in the sand' (from the folk belief that ostriches hide from danger this way) means to refuse to face reality.
In modern usage, 'sand' has acquired technical senses in engineering and geology. Geologically, 'sand' denotes a specific particle size range (0.0625 to 2 millimeters in diameter), between 'silt' (finer) and 'gravel' (coarser). This precision matters because sand's engineering properties — drainage, load-bearing capacity, compaction behavior — depend critically on particle size. Sand is the most consumed natural resource on Earth after water, used in concrete, glass, electronics (silicon from sand), and land reclamation, making it a strategic material whose supply is increasingly contested worldwide.