from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. A staining technique used to classify bacteria in which a bacterial specimen is first stained with crystal violet, then treated with an iodine solution, decolorized with alcohol, and counterstained with safranine. Gram-positive bacteria retain the violet stain; gram-negative bacteria do not.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A staining technique, using a sequence of crystal violet, iodine and safranine, used to differentiate bacteria into two large groups of species.

from The Century Dictionary and Cyclopedia

  • n. See Gram's method, stain.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. a staining technique used to classify bacteria; bacteria are stained with gentian violet and then treated with Gram's solution; after being decolorized with alcohol and treated with safranine and washed in water, those that retain the gentian violet are Gram-positive and those that do not retain it are Gram-negative


After Hans Christian Joachim Gram (1853-1938), Danish physician.
(American Heritage® Dictionary of the English Language, Fourth Edition)
from Hans Christian Gram Danish bacteriologist. (Wiktionary)


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