Go to MSN Homeencarta®
Dictionary
Find
in
Dictionary
Thesaurus
Translations
ABCDEFGHIJKLMNOPQRSTUVWXYZ
Click to move up the list of words
half-hardy
half-hearted
half hitch
half-holiday
half-hour
half-inch
half-jack
half-length
half-life
half-light
half-line
half-marathon
half-mast
half measure
half-moon
half nelson
half note
Click to move down the list of words
Also available:

World English Dictionary
Dictionnaire Français

half-life
half-life (plural half-lives)


noun 
Definition:
 
1. time taken to lose half of radioactivity: the time a radioactive substance takes to lose half its radioactivity through decay.
Symbol  T1/2
2. time taken to lose half of drug: the time it takes for half a given amount of a substance such as a drug to be removed from living tissue through natural biological activity
Encarta® World English Dictionary [North American Edition] © & (P)2009 Microsoft Corporation. All rights reserved. Developed for Microsoft by Bloomsbury Publishing Plc.
Advertisement
© 2009 Microsoft