Talk:permille
Choosing the main spelling
editpermille, per mille, per mil, per mill at the Google Books Ngram Viewer. suggests permille is the rarest. Changing this to 30 permille, 30 per mille, 30 per mil, 30 per mill at the Google Books Ngram Viewer. only finds 30 per mil and 30 per mille in this order; similarly for 3 permille,3 per mille,3 per mil,3 per mill at the Google Books Ngram Viewer., which finds 3 per mille and 3 per mil.
Going by frequency alone, per mil would be the winner, followed by per mille catching on it recently; per mill comes third, and permille is last by a wide margin.
per mil is in Lexico[1], Collins[2] and Cambridge[3]; not in M-W.
per mille is in Lexico[4] and Cambridge[5]; not in M-W. It is the title of W:Per mille. mille is Latin for thousand.
per mill is in M-W[6], Lexico[7], and Collins[8].
permille is not in any of the major OneLook dictionaries: “permille”, in OneLook Dictionary Search.. It would be an analog of percent; in percent, per cent at the Google Books Ngram Viewer., percent overtook per cent in 1972.
Interestingly, per WP, "the term occurs so rarely in English that major dictionaries do not agree on the spelling or pronunciation even within a single dialect of English[7] and some major dictionaries such as Macmillan[8] and Longman[9] do not even contain an entry"; that would be interesting information to have in Wiktionary.
--Dan Polansky (talk) 06:50, 8 May 2020 (UTC)
Assuming it is a tie between per mil and per mille, we need some additional arbitrary input to decide. I would decide for per mille, rather arbitrarily, following the cues: 1) mille is in the etymology, 2) multiple European languages have a term ending in -e or -a (Czech promile, Danish promille, Dutch promille, Faroese promilla, Finnish promille, French pour mille, German Promille, Russian промилле (promille), Swedish promille), and the use of the term seems to be driven by uses in continental Europe if one believes WP, "The term is more common in other European languages where it is used to express percentages smaller than 1%. One common usage is blood alcohol content, that is usually expressed as a percentage in English-speaking countries." --Dan Polansky (talk) 07:07, 8 May 2020 (UTC)