- Mesial
- Meson
- Mesozoic
- Mess up
- Met allophone
- Meta
- Metachysis
- Metadata
- Metal bar
- Metalhead
- Metalloid
- Metallurgical
- Metals
- Metamorphose
- Metaphorically
- Metaphysician
- Metastasis
- Metempsychosis
- Meteor
- Meteoric
- Meteorite
- Meteorology
- Methinks
- Methyl alcohol
- Meticulous
- Metre in verse
- Metrical
- Metropolitan
- Mettle
- Mewing
- Mexican mint
- Mezzaine
- Mhz
- Miasma
- Michaelmas
- Mickle
- Microbial
- Microcephalous
- Microcosmography
- Micrograph
- Micron
- Microsoft
- Microspore
- Microwave
- Mid-day nap
- Mid-off
- Midday
- Middle age
- Middle-east
- Middle-sized
- Middleman
- Midfield
- Midmost
- Midsummer
- Midsummer day
- Midtown
- Midway
- Midwife
- Mien
- Migrant
- Migrant labourers
- Miler
- Milf
- Milieu
- Militancy
- Muscle
- Muscle-man
- Muse
- Museology
- Museum piece
- Music stand
- Musical
- Musical rhythm
- Musical variety
- Musk
- Musk-deer
- Musk-rat
- Musket
- Muslim
- Mussitate
- Must
- Mustang
- Mustiness
- Mutawa
- Mute
- Mutely
- Mutilate
- Mutineer
- Mutter
- Muttering
- Muttering prayer
- Muttering prayers
- Mutton
- Mutton dressed as a lamb
- Mutual consent
- Mutualism
- Mutually
- Muzzle
- Muzzy
- My lord