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English Words Starting With M

8,594 entries — pick a word to see its definition, pronunciation, and usage.

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Noun Verb Adjective Adverb Plural noun Combining form Verb (transitive)Verb (intransitive)Verb (ambitransitive)

mesopause
nounVery Low
/ˈmɛzə(ʊ)pɔːz/The boundary in the Earth's atmosphere between the mesosphere and the thermosphere, characterized by a temperature minimum.
mesopeak
nounExtremely Rare / Obscure Technical
/ˈmɛsə(ʊ)piːk/The middle or central part of a mountain's summit ridge or peak.
mesophile
adjectivenounC2/Technical
/ˈmɛsə(ʊ)fʌɪl/An organism that thrives in moderate temperatures, typically between 20°C and 45°C.
mesophyll
nounC1
/ˈmɛsə(ʊ)fɪl/The inner tissue of a plant leaf, located between the upper and lower epidermis, where photosynthesis primarily occurs.
mesophyte
nounC2
/ˈmɛsə(ʊ)ˌfʌɪt/A plant that grows in conditions of moderate moisture, neither very wet nor very dry.
mesoplankton
nounC2
/ˌmɛzəʊˈplæŋ(k)tən/, /ˌmɛsəʊ-/The community of planktonic organisms that inhabit the middle depths of a body of water, typically below the surface layer but above the deep sea floor.
mesopotamia
nounLow
/ˌmɛs.ə.pəˈteɪ.mi.ə/A historical region in Western Asia situated between the Tigris and Euphrates rivers, often called the 'cradle of civilization'.
mesorectum
nounVery Rare
/ˌmɛsəʊˈrɛktəm/The fatty and connective tissue layer (mesentery) surrounding the rectum.
mesosome
nounVery Low
/ˈmɛsə(ʊ)səʊm/A non-natural, artefactual structure in bacteria, produced by chemical fixation for electron microscopy, once thought to be a functional organelle.
mesosphere
nounC2
/ˈmɛsəʊsfɪə/The layer of Earth's atmosphere above the stratosphere and below the thermosphere, where temperature decreases with altitude.
mesothelioma
nounC2
/ˌmɛz.ə.θiː.liˈəʊ.mə/A rare and aggressive type of cancer that develops in the thin layer of tissue (mesothelium) that covers many internal organs.
mesothelium
nounLow
/ˌmɛsə(ʊ)ˈθiːlɪəm/A membrane of simple squamous epithelial cells that lines certain internal body cavities.
mesotherapy
nounLow
/ˌmɛsə(ʊ)ˈθɛrəpi/A cosmetic or medical treatment involving multiple micro-injections of vitamins, enzymes, hormones, and plant extracts into the mesoderm (middle layer of skin) to treat various conditions.
mesothorax
nounVery low
/ˌmɛsəʊˈθɔːræks/The middle segment of the three segments of an insect's thorax.
mesothorium
nounExtremely low (Technical/Scientific)
/ˌmɛsəʊˈθɔːrɪəm/A radioactive isotope formed as an intermediate in the decay chain of thorium.
mesotron
nounC2+ / Extremely Rare
/ˈmɛzətrɒn/An antiquated name for the subatomic particle now universally known as the 'meson', specifically the pion.
mesovarium
nounVery Low
/ˌmɛsəʊˈveərɪəm/The specific portion of the broad ligament that supports the ovary in female mammals.
mesovortex
nounVery Low
/ˈmɛsəʊˌvɔːtɛks/A small-scale rotating weather system, typically between 2 and 10 kilometres in diameter, found within larger convective storms.
mesozoa
nounVery Low
/ˌmɛsə(ʊ)ˈzəʊə/A taxonomic group of minute, parasitic worm-like animals, considered a phylum or subkingdom of simple invertebrates.
mesozoan
adjectivenounVery low
/ˌmɛsə(ʊ)ˈzəʊən/A tiny, parasitic worm-like organism belonging to the phylum Mesozoa.

Showing 4021–4040 of 8594 words.