== M ==
;m:metreMetre, SI unit of length;MDFmg:medium-density fiberboardMilligram;mgml:milligramMililitre;mlMS:mililitreMotor Ship;MV:Motor Vessel;min:minuteMinute;MCR:Maximum continuous rating;MDF:Medium-density fiberboard
;Modulus:(Young's modulus) - Tensile elasticity, the tendency of an object to deform along an axis
;mol:moleMole, SI unit of amount of substance;MOPS:Minimum Operational Performance Standards;mph:miles Miles per hour;MARPOL:International Convention for the Prevention of Pollution from Ships
== N ==