Ma, macrokarst, macropore, magnesian limestone, magnesite, magnetic north, malachite, mammals, manatial, Manning equation, manometer, mantled karst, marble, marginal polje, marine relict, marine water, marker bed, marl, mass curve, mass density, mass flowmeter, massive structure, master cave, match point, matric potential, matrix, maximum basin relief, maze cave, maze cave pattern, mean deviation, mean value, meander, meander belt, meander niche, meandering karren, measuring flume, measuring weir, mechanical ascender, mechanical cover, mechanical dispersion, mechanical dispersion, coefficient, median, medicinal spring, medium sand, Meinzer unit, melanterite, melting, melting point, meltwater, meniscus, mercury column, mercury injection method, merokarst, mesh, mesophyte, metabolic rate, metabolism, metamorphosis, meteoric water, meteorology, mexican onyx, micrite, microclimate, microgour, microhabitat, microkarren, microkarst, microspar, middens, migration, mine drainage, mine water, mineral spring, minerals, mining of ground water, minor karst features, mirabilite, Mischungskorrosion, miscible, miscible displacement, mixing length, mixture corrosion, mode, model, model technique, mogote, moisture content, moisture deficiency, moisture equivalent, moisture tension, moisture volume percentage, moisture weight percentage, mold, molecular diffusion (diffusion), molecular diffusion, coefficient of, molecule, mollisol, monetite, monohydrocalcite, monomolecular film, montgomeryite, montmorillonite, moonmilk, moor, moraine, morphometric analysis, moulin, mountain milk, mud, mud crack, mud pendulite, mud stalagmite, mudflow, multiaquifer formation, multiaquifer well, mutation, My,