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say it: uh
a is a noun meaning "a metric unit of length equal to one ten billionth of a meter (or 0.0001 micron); used to specify wavelengths of electromagnetic radiation". It carries 7 recorded senses.
a metric unit of length equal to one ten billionth of a meter (or 0.0001 micron); used to specify wavelengths of electromagnetic radiation
any of several fat-soluble vitamins essential for normal vision; prevents night blindness or inflammation or dryness of the eyes
one of the four nucleotides used in building DNA; all four nucleotides have a common phosphate group and a sugar (ribose)
the basic unit of electric current adopted under the Systeme International d'Unites
“a typical household circuit carries 15 to 50 amps”
the 1st letter of the Roman alphabet
the blood group whose red cells carry the A antigen
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for a come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.