age-old
One very long word that starts with m is: microcryptocrystalline (22 letters)
A very popular toy that starts with the letter U is UNO. Another toy that starts with the letter U is Uncle Goose.
Another word for meat is flesh.But, as the question is not very precise, another word using the letters meat is team!
Very probable this is ununoctium (atomic number 118, now has not another name).
Explicit is a synonym for very precise. It begins with the letters ex.
very, vast, vice
This is not a very good question.
awful?
Slid
numerous
gelid
naseberry