The word 'gross' as a unit of quantity — 144 items, a dozen dozens — entered English in the fifteenth century from Old French 'grosse douzaine,' literally 'large dozen' or 'great dozen.' The adjective 'gros' (large, thick, coarse) descends from Late Latin 'grossus' (thick, coarse), a word of uncertain ultimate origin, possibly from a pre-Latin substrate language.
The gross was a standard unit in European wholesale trade, sitting naturally in the duodecimal (base-12) counting system that pervaded commerce from the Middle Ages onward. Just as a dozen (12) was the basic commercial grouping, the gross (12 × 12 = 144) was the large-scale grouping, and the great gross (12 × 144 = 1,728) was used for very large orders. The system was practical: small items like buttons, pins, nails, screws, and pencils were manufactured and sold by the gross well into the twentieth century. The term remains in use in some wholesale industries
The same Old French 'gros' (large) gave English several other words, each preserving a different facet of 'largeness.' 'Gross' as an adjective meaning 'total, before deductions' (gross income, gross weight) preserves the sense of 'the large, overall figure.' 'Gross' meaning 'flagrant' or 'obvious' (gross negligence, gross misconduct) preserves the sense of 'large-scale, impossible to miss.' 'Gross' meaning 'disgusting' or 'vulgar' (attested from the sixteenth century) extends from 'coarse' and 'unrefined,' the pejorative side of '
The most surprising relative is 'grocer.' Old French 'grossier' meant a wholesale dealer — someone who sold goods 'en gros' (in bulk, by the gross). The word entered English in the fourteenth century with this wholesale meaning. Over the following centuries, the 'grocer' gradually transformed from a bulk trader into a retail shopkeeper selling foodstuffs in small quantities, a complete inversion of the word's original sense. 'Grocery' (the goods sold by a grocer, or the shop
The verb 'engross' also derives from 'gros.' In its oldest sense, to engross a document meant to write it out in large, clear letters (the 'engrossed' copy being the formal, large-format version). It later came to mean 'to absorb completely' — to take up in large measure — as in 'the book engrossed her attention.' The legal sense of engrossing (buying up large quantities to corner a market) preserves the wholesale-trade origin most directly
The gross as a counting unit declined with the adoption of the metric system and decimal-based commerce in most of the world, but it persists in anglophone trade and in figurative speech. The informal use of 'gross' to mean 'disgusting' — especially popular in American English since the mid-twentieth century — has become the word's most familiar sense for younger speakers, who may not know that 144 buttons once came bundled under the same name.