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[lak-teys, -teyz] /ˈlæk teɪs, -ˌteɪz/
noun, Biochemistry
an enzyme capable of hydrolyzing lactose into glucose and galactose.
Origin of lactase
1890-95; lact- + -ase Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for lactase
  • Lactose intolerance happens when the small intestine does not make enough of the enzyme lactase.
  • They will need to be given supplements with the enzyme lactase so that they can tolerate milk products.
  • Babies always made lactase, the enzyme that breaks down this sugar, but after weaning lactase production would stop.
  • lactase enzyme preparations are used to reduce the lactose content of milk and milk-derived food products.
British Dictionary definitions for lactase


/ˈlækteɪs; -teɪz/
any of a group of enzymes that hydrolyse lactose to glucose and galactose
Word Origin
C20: from lacto- + -ase
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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lactase in Medicine

lactase lac·tase (lāk'tās')
See beta-galactosidase.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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lactase in Science
An enzyme that is found in the small intestine, liver, and kidneys of mammals and catalyzes the breakdown of lactose into galactose and glucose.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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