Definition of A
1. Noun. A metric unit of length equal to one ten billionth of a meter (or 0.0001 micron); used to specify wavelengths of electromagnetic radiation.
Generic synonyms: Metric Linear Unit
Terms within: Micromicron, Picometer, Picometre
Group relationships: Micromillimeter, Micromillimetre, Millimicron, Nanometer, Nanometre, Nm
2. Noun. Any of several fat-soluble vitamins essential for normal vision; prevents night blindness or inflammation or dryness of the eyes.
Generic synonyms: Fat-soluble Vitamin
Specialized synonyms: Retinol, Vitamin A1, Dehydroretinol, Vitamin A2
3. Noun. One of the four nucleotides used in building DNA; all four nucleotides have a common phosphate group and a sugar (ribose).
4. Noun. (biochemistry) purine base found in DNA and RNA; pairs with thymine in DNA and with uracil in RNA.
Category relationships: Biochemistry
Generic synonyms: Purine
Substance meronyms: Deoxyribonucleic Acid, Desoxyribonucleic Acid, Dna, Ribonucleic Acid, Rna
5. Noun. The basic unit of electric current adopted under the Systeme International d'Unites. "A typical household circuit carries 15 to 50 amps"
Generic synonyms: Current Unit
Terms within: Ma, Milliampere
Group relationships: Abamp, Abampere
6. Noun. The 1st letter of the Roman alphabet.
Generic synonyms: Alphabetic Character, Letter, Letter Of The Alphabet
7. Noun. The blood group whose red cells carry the A antigen.
Definition of A
1. prep. In; on; at; by.
Definition of A
1. Letter. (Latn-def en letter 1 a) ¹
2. Number. (Latn-def en ordinal 1 a) ¹
3. Symbol. The highest rank on any of various scales that assign letters. ¹
4. Symbol. (context education) The highest letter grade assigned (disregarding plusses and minuses). ¹
5. Symbol. (music) A tone three fifths above C in the cycle of fifths; the sixth tone of the C major scale; the reference tone that occurs at exactly 440 Hz; the printed or written note A. ¹
6. Symbol. (medicine) A blood type that has a specific antigen that aggravates the immune response in people with type B antigen in their blood. They may receive blood from type A or type O, but cannot receive blood from AB or B. ¹
7. Symbol. (chemistry) mass number Mass number. ¹
8. Abbreviation. Ace ¹
9. Abbreviation. Acre ¹
10. Abbreviation. Ammeter ¹
11. Abbreviation. (physics) angstrom ¹
12. Abbreviation. Answer ¹
13. Abbreviation. (geometry) area Area ¹
14. Abbreviation. (sports) An assist ¹
15. Abbreviation. (context weaponry) atom; atomic ¹
16. Abbreviation. (context vehicle-distinguishing signs) Austria ¹
17. Letter. (Latn-def en letter 1 a) ¹
18. Cardinal number. (Latn-def en ordinal 1 a) ¹
19. Noun. (Latn-def en name A a) ¹
20. Noun. A spoken sound represented by the letter ''a'' or ''A'', as in map, mall, or male. ¹
21. Noun. A written representation of the letter ''A'' or ''a''. ¹
22. Noun. (context: printing) A printer's type or stamp used to reproduce the letter ''a''. ¹
23. Article. One; any indefinite example of; used to denote a singular item of a group. ¹
24. Article. (non-gloss definition Used in conjunction with the adjectives score, dozen, hundred, thousand, and million, as a function word.) ¹
25. Article. One certain or particular; any single. ¹
26. Article. The same; one. ¹
27. Article. Any, every. ¹
28. Article. (non-gloss definition Used before plural nouns modified by few, good many, couple, great many, etc.) ¹
29. Article. (non-gloss definition Used before a proper noun to create an example out of it.) ¹
30. Preposition. (archaic) In, on, at, by. ¹
31. Preposition. (archaic) In the process of; in the act of; into; to. (qualifier Used with verbal substantives in ''-ing'' which begin with a consonant.) ¹
32. Preposition. To, each, per. ¹
33. Verb. (archaic or slang) Have. (qualifier Now often attached to preceding auxiliary verb.) ¹
34. Pronoun. (obsolete except British Scotland dialectal) He. ¹
35. Pronoun. (obsolete except British Scotland dialectal) She. ¹
36. Pronoun. (obsolete except British Scotland dialectal) They; them. ¹
37. Pronoun. (obsolete except British Scotland dialectal) It. ¹
38. Pronoun. (obsolete except British Scotland dialectal) I. ¹
39. Interjection. A meaningless syllable; ah. ¹
40. Preposition. (context: archaic slang) Of. ¹
41. Adverb. (context: chiefly Scotland) All. ¹
42. Adjective. (context: chiefly Scotland) All. ¹
43. Abbreviation. An are, a unit of area of which 100 comprise a hectare. ¹
¹ Source: wiktionary.com
Medical Definition of A
1. First letter of the Greek alphabet, alpha, used as a classifier in the nomenclature of many sciences.
2. Symbol for atto-, Bunsen's solubility coefficient, specific optical rotation, absorbance, specific absorption coefficient, degree of dissociation, adenosine or adenylic acid in polynucleotides, alanine in polypeptides, first substrate in a multisubstrate enzyme=catalyzed reaction
3. In chemistry, denotes the first in a series, a position immediately adjacent to a carboxyl group, the first of a series of closely related compounds, an aromatic substituent on an aliphatic chain, or the direction of a chemical bond away from the viewer.
Click the following link to bring up a new window with an automated collection of images related to the term: A Images
Lexicographical Neighbors of A
a (current term)