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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)

molecular beam
nounC2
/məˌlek.jə.lə ˈbiːm/A directed stream of molecules moving in a vacuum with minimal collisions.
molecular biology
nounLow-Mid (Specialist)
/məˌlɛkjʊlə baɪˈɒlədʒi/The branch of biology that deals with the structure and function of the macromolecules (e.g., proteins and nucleic acids) essential to life.
molecular clock
nounC1/C2
/məˈlekjʊlə klɒk/A technique in evolutionary biology that uses the constant rate of mutation in DNA sequences to estimate the time when species diverged from a common ancestor.
molecular cloud
nounC1-C2
/məˌlek.jə.lə ˈklaʊd/A dense region of gas and dust in interstellar space where molecules are abundant and stars can form.
molecular distillation
nounVery Low
/məˈlek.jə.lə ˌdɪs.tɪˈleɪ.ʃən/A separation technique in which substances are vaporised and condensed over very short distances under high vacuum, used to purify temperature-sensitive compounds.
molecular film
nounC2
/məˌlek.jə.lə ˈfɪlm/An extremely thin layer, typically one molecule thick, adhering to a surface.
molecular formula
nounC2
/məˌlek.jə.lə ˈfɔː.mjə.lə/A notation that indicates the types and numbers of atoms in a molecule, without showing its structure.
molecular genetics
nounC1/C2
/məˌlek.jə.lə dʒəˈnet.ɪks/The branch of genetics that studies the structure and function of genes at the molecular level, focusing on DNA, RNA, and protein synthesis.
molecular knife
nounLow
/məˌlek.jə.lə ˈnaɪf/A protein or enzyme that cuts DNA at specific sequences, used in genetic engineering.
molecular medicine
nounLow
/məˌlek.jə.lə ˈmed.ɪ.sən/A branch of medicine that studies disease mechanisms and develops treatments at the molecular and genetic level.
molecular sieve
nounC1
/məˌlek.jə.lə ˈsiːv/A material with a very regular, porous structure that acts like a filter at the molecular level, used to separate molecules based on their size and shape.
molecular spectrum
nounLow
/məˈlekjʊlə ˈspektrəm/The pattern of light absorbed or emitted by a substance due to changes in the energy levels of its molecules.
molecular volume
nounC2 (Very Low Frequency in General English)
/məˌlek.jə.lə ˈvɒl.juːm/The volume occupied by one mole of a substance under specific conditions.
molecular weight
nounTechnical
/məˈlek.jə.lə weɪt/The mass of a single molecule of a substance, expressed in atomic mass units (amu) or Daltons (Da). It is calculated by summing the atomic weights of all atoms in the molecule's chemical formula.
molecularity
nounC2
/məˌlɛkjʊˈlærɪti/The number of molecules that participate as reactants in an elementary chemical reaction.
molecule
nounC1
/ˈmɒl.ɪ.kjuːl/The smallest physical unit of a chemical element or compound, consisting of two or more atoms held together by chemical bonds.
molehill
nounlow
/ˈməʊlhɪl/A small mound of earth thrown up by a mole burrowing underground.
moleskin
nounC1
/ˈməʊlskɪn/A strong, durable cotton fabric with a soft, brushed surface, traditionally used for hard-wearing trousers and jackets.
moleskins
plural-nounC1
/ˈməʊlskɪnz/A strong, durable cotton fabric with a soft, brushed surface, traditionally used for work trousers.
molest
verbverb-transitiveC1
/məˈlɛst/To subject someone to unwanted and harmful sexual interference or assault.

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