- marrow
- marsh
- marshal
- martin
- martyr
- mason's rule
- mass
- mass media
- massive
- master
- masterpiece
- mat for sleeping
- match up to
- match-stick
- matching-gun
- matchmaker
- matter
- matter of record
- matzo
- mazily
- mb
- measured
- mechanistic
- meddlesome
- mediation
- medicaid
- meditative
- medom
- meek
- meet
- meet someone halfway
- meet the eye
- megalith
- megatrend
- melancholy
- mélange
- melodious
- memento
- memorable
- memorandum
- memorialise
- memorised
- memorising
- mendacious
- mensurable
- mental acumen
- mephitic
- mephitis
- merchant chief
- merciless
- mercy
- meretricious
- merge
- merino
- merlin
- mesentery
- messily
- messy
- metadata
- metal pot
- metallic
- metastasize
- metathesis
- miasmatic
- miasmic, miasmal
- microprocessor
- mid section
- mid-may
- mid-off
- middle line
- middle-manship
- midnight
- midsummer
- mightily
- militant
- militarize
- millennial
- miller
- millinery
- milnea
- mincing
- mind
- minesweeper
- miniature
- minister
- minuend
- miracle
- miraculous
- mirror
- misandry
- misapprehensive
- misbehaviour
- miscarriage
- miscellaneousness
- misconduct
- misconstruction
- misconstrue
- miscount
- misgiving
- mishap