| M | 1,000 
| Others |
| M | 1000 (Roman numeral)
| Others |
| M | Chief of the British Secret Service
| Others |
| M | Macadamia
| Others |
| M | Mach
| Others |
| M | Mach number
| Others |
| M | Machine
| Others |
| M | Macy's, Inc.
| Others |
| M | Madrid
| Others |
| M | Magenta
| Others |
| M | Magic
| Others |
| M | Maiden
| Others |
| M | Maintainability
| Others |
| M | Major cycle
| Others |
| M | Making
| Others |
| M | Male
| Biology |
| M | Man
| Others |
| M | Managing
| Others |
| M | Manchester
| Others |
| M | Mandatory
| Others |
| M | Maneuver
| Others |
| M | Maniacal
| Others |
| M | Manic
| Others |
| M | Manifold
| Others |
| M | Manservant
| Others |
| M | Manual
| Others |
| M | Manufacturer
| Others |
| M | Manure
| Others |
| M | Maple Common binary file
| Others |
| M | Maritime
| Others |
| M | Mark
| Others |
| M | Marketing
| Others |
| M | Markovian
| Others |
| M | Married
| Others |
| M | Mars
| Others |
| M | Martin
| Others |
| M | Marvelous
| Others |
| M | Mass
| Others |
| m | Mass (as in E=mc^2)
| Others |
| M | Mathematica Standard package
| Others |
| M | Matlab M-file Function and commands
| Others |
| M | Matrix
| Others |
| M | Matt
| Others |
| M | Matthew
| Others |
| M | Mature
| Others |
| M | Maxim
| Others |
| M | Maybe
| Others |
| M | Mean anomaly
| Others |
| M | Meaning
| Others |
| M | Mechanized
| Others |
| M | Media
| Others |
| M | Medicine
| Others |
| M | Mediocre
| Others |
| M | Mediocrity
| Others |
| M | Meditation
| Others |
| M | Medium
| Others |
| M | Mega
| Others |
| M | Megawatt
| Others |
| M | Memory
| Others |
| M | Mercedes
| Others |
| M | Mercurius
| Others |
| M | Meridie
| Others |
| M | Meta
| Others |
| M | Metaphysical
| Others |
| M | Meter
| Others |
| M | Meters
| Others |
| M | Methionine
| Others |
| M | Method
| Others |
| M | Methyl
| Others |
| m | Metre
| Others |
| m | Metre/Meter
| Others |
| M | Metri
| Others |
| M | Michael
| Others |
| M | Middle
| Others |
| M | Middle Name
| Others |
| M | Mifune
| Others |
| M | Mighty
| Others |
| M | Miladi
| Others |
| M | Milan
| Others |
| M | Milk
| Others |
| M | Mille
| Others |
| M | Millennium
| Others |
| m | Milli
| Others |
| m | MILLI-
| Others |
| M | Million
| Others |
| m | Minute
| Others |
| M | Minutes
| Others |
| M | Miranda programming language Script file
| Others |
| M | Misdemeanor
| Others |
| M | Miserable
| Others |
| M | Misery
| Others |
| M | Misguided
| Others |
| M | Missing data
| Others |
| M | Mission
| Others |
| M | Missionary
| Others |
| M | Misunderstood
| Others |
| M | Mix
| Others |
| m | mobile
| Others |
| M | Model
| Others |
| M | Modern
| Others |
| M | Module
| Others |
| M | Molar
| Others |
| M | Molecular
| Others |
| M | Molto (Italian coin grade equivalent to Good)
| Others |
| M | Monday
| Others |
| M | Monitor
| Others |
| M | Monocytes
| Others |
| M | Months
| Others |
| M | Moronic
| Others |
| M | Motivation
| Others |
| M | Motor
| Others |
| M | Motorsport
| Others |
| M | Mozilla
| Others |
| M | Mud, Muddy
| Others |
| M | Multimedia
| Others |
| M | Multiplayer
| Others |
| M | Multiple
| Others |
| M | Multiply
| Others |
| M | Munich
| Others |
| M | Murder
| Others |
| M | Murderer
| Others |
| M | Muscle
| Others |
| M | Music
| Others |
| M | Mutual
| Others |
| M | Mystery
| Others |
| M | Nautical mile
| Others |
| M | Negative connection
| Others |
| M | Number of Revolutions Required for the Rendezvous
| Others |
| M | one thousand
| Others |
| M | The Maintenance
| Others |
| M | The Multiplicative
| Others |
| M | Thousand (Roman Numeral)
| Others |
| M | Up to 81 mph
| Others |
| M$ | Micronation Dollar
| Others |
| M$ | Micronational dollar
| Others |
| M- | Mega (1 Million)
| Others |
| M- | Mega (1 Million) (prefix)
| Others |
| M- | Motorway
| Others |
| M- | Time in Days Before Move Operations
| Others |
| M-) | See no evil
| Others |
| M. | A Major Interval
| Others |
| M. | A Minor Interval
| Others |
| m. | Mane In the morning
| Others |
| m. | maskulin
| Others |
| M. | misce - mix
| Others |
| m. | mit
| Others |
| M:-) | A salute
| Others |