One six-letter word with "m" as the second letter is "flame."
dermal
morons.
mimosa
bottom
mimosa
Modern
Harlem
How about rhythm
Some five letter words with O and M as the second and third letter are:combocometcommacomicdomedhomerhomeymommynomadoomphromanromeorompervomitwomanwomen
impel
One option is mayhem.
raCisM racism