- multiform
- magnetic personality
- mass action
- make it too hot for
- metallic sound
- modern era
- manometer
- minor premise
- morphia
- margrave
- moir
- mongraphist
- memorise
- most common recent ancestor
- maraud
- myopia
- monotreme
- miscegenation
- mythopoetic
- month of sundays
- make a mess
- mysophobia
- maiden name
- muck heap
- myrmecophobia
- mediterranean
- magnate
- magnetic disk
- magnetic stripe
- magnetism
- mainland
- mainly
- make a killing
- make a monkey of
- make a mountain of a molehill
- make do
- make for
- make or break
- make out
- malpractice
- maltreatment
- man of means
- man of moods
- man of words
- man to man
- man-sized
- manipulator
- mannequin
- mannerism
- mason bee
- mast
- masterly
- mastery
- masthead
- mat of reeds
- mattress
- maverick
- maw
- may
- mayhem
- mayonnaise
- maypole
- mazy
- meadow
- meager
- meal ticket
- mealtime
- meander
- melody
- melt
- menstruate
- menstruation
- mensuration
- mensus
- mental reflection
- menthol
- mephistophelian
- metallurgy
- metaphorical
- micron
- microscopically
- mid-calf
- milk
- milk tooth
- milkman
- milksop
- millstone
- mime
- minced meat
- mire
- misappropriate
- misappropriation
- misinform
- mislead
- misogamist
- misogynist
- misquote
- mixed blessing
- mixed blood