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!

Qenya 

mal(de)

adverb. how, in what manner

The correlative ᴹQ. mal or malde “how, in what manner” appeared in Demonstrative, Relative, and Correlative Stems (DRC) from 1948 (PE23/111), a combination of interrogative ᴹQ. ma and ᴹQ. -l(de) “way, manner”.

Neo-Quenya: For purposes of Neo-Quenya I would update this to ᴺQ. manallë “somehow, in some way” using the later suffix Q. -llë.