2803: Famous Fractions

All numbers can be made fractional, so three becomes a fifth, twelve to a twelfth. Some numbers though are so apparently natural as to get their own words. Many languages have a distinct words for ‘half’ to the point that, in English, it would not be an option to say ½ as “a second”. Second to having a word for ‘half’ that doesn’t fit the normal pattern is having a word like in English, ‘quarter’, though here to say “a fourth” is perfectly acceptable too. ‘Third’, too, is distinct but this has to do mostly with metathesis from it earlier being a thrid’ from an even earlier thrith (or thrið). For a much longer list of other languages that do this, scroll to the end. 

Elsewhere, English also has numbers for certain lump amounts, but these don’t line up. In units of years, there are the base-10 decade, century, and millennium, but in terms of objects there are dozen, score, and gross (12, 20, & 144 [a dozen dozens] respectively). Because these systems don’t line up neatly they can be combined for more colloquial ways of saying certain other frequently used amounts, like how a half-dozen is 6 and a quarter-century is 25 years.

Back to the phenomenon of half and quarter, and very occasionally third, getting words that don’t fit the normal paradigm, see how it pops up all over the world in languages and cultures that would have had little interaction to prove that it is apparently quite a natural progression. 

French:

Half: Moitié (does not fit the "demi-" pattern used for other fractions)

Quarter: Quart (a distinct word, not a derivative of "fourth")

Other Fractions: Tiers (third), Cinquième (fifth), etc.

Spanish:

Half: Mitad (distinct from "medio")

Quarter: Cuarto (while derived from "cuatro," it is a specific term for one-fourth)

Other Fractions: Tercio (third), Quinto (fifth), etc.

Russian:

Half: Половина (Polovina; doesn't follow the usual ordinal fraction pattern)

Quarter: Четверть (Chetvert'; a special term, not the expected "четвёртая" for fourth)

Other Fractions: Треть (third), Пятая (fifth), etc.

Outside of European languages, this is still common, far and away with the word for ½ as with Japanese, Korean, Finnish and Mandarin, but it is even common to see a quarter have its own word, which appears in Thai, Wolof (in West Africa), Zulu.