| mullion | ลูกฟัก (หน้าต่าง) |
| municipality | เทศบาล |
| mushroom slab | แผ่นพื้นไร้คาน (รูปดอกเห็ด) |
| Mass: | (english) A property of an object measured by the degree that it resists acceleration. |
| Magnitude: | (english) A scalar value having physical units. |
| Modulus of elasticity: | (english) The proportional constant between stress and strain for material with linear elastic behavior: calculated as stress divided by strain. Modulus of elasticity can be interpreted as the slope of the stress-strain graph. It is usually denoted as E, sometimes known as Young's Modulus Y, or E-Modulus. |
| Moment: | (english) The resultant of a system of forces causing rotation without translation. A moment can be expressed as a couple. |
| Moment of inertia (I): | (english) Moment of inertia has two distinct but related meanings: 1) it is a property of a an object relating to the magnitude of the moment required to rotate the object and overcome its inertia. 2) A property of a two dimensional cross section shape with respect to an axis, usually an axis through the centroid of the shape. |
| Mass balance | (Environmental Engineering) An organized accounting of all inputs and outputs to an arbitrary but defined system. Stated in other terms, the rate of mass accumulation within a system is equal to the rate of mass input less the rate of mass output plus the rate of mass generation within the system. |
| Maximum contaminant level (MCL) | (Environmental Engineering) The maximum allowable concentration of a given constituent in potable water. |