Beware, older languages below! The languages below were invented during Tolkien's earlier period and should be used with caution. Remember to never, ever mix words from different languages!

Gnomish

odinthos

cardinal. seventeen

The Gnomish Lexicon of the 1910s had odinthos “seventeen”, originally a combination of G. odin “seven” and G. sath “ten”, but then the ns > nth, after which the final th dissimilated to s: odinsath > odinthath > odinthas (GG/13). Then at some point the a in the final syllable became o, producing a suffix -thos also seen in other Gnomish “teen” words.