If you love words and love numbers then unusual number words are the tops!
Today's both have interesting histories.
Twain
Mark Twain famously took 'Mark Twain' as his pen name, after hearing it used on Mississippi steamboats to mean a water depth of two fathoms (measured by the second mark on a plumbline).
There is an archaic ring to 'twain', and it is a fossil word, now mainly used in formulaic phrases like 'cleave in twain' and rare, at 0.3 occurrences per million words.
Originally it just meant 'two', but not just two of any old thing, it was two things with masculine grammatical gender. In Old English nouns were masculine, feminine or neuter, as in modern German. Two (and three) were adjectives and had to agree with the thing they were describing, so we had twegen (M), twa (F) and tu (N). (It's actually a bit more complicated, because they also had to agree as to grammatical case, but you get the idea.)
Here are examples, courtesy of AI Overview
- Twegen cnitas
- Twa cwena
- Tu scipu
(A knight was originally a boy (like modern German Knabe) but later changed its meaning.)
The masculine twegen survived as twain, but with a slightly different meaning, and the other forms became modern two. Its survival may have beed aided by its use in the King James' Bible, which intentionally used archaic language.
Thrin