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Pm

Symbol, Chemistry

pm.

1.

P.M.

1.
Past Master.
2.
3.
p.m.
4.
Police Magistrate.
6.
post-mortem.
7.
Prime Minister.
8.
Provost Marshal.

p.m.

1.
after noon.
2.
the period between noon and midnight.
Origin
< Latin post merīdiem
Usage note
See a.m.
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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British Dictionary definitions for Pm

pm1

abbreviation
1.
premium

pm2

abbreviation
1.
St Pierre and Miquelon

Pm

Chemical symbol
1.
promethium

PM

abbreviation
1.
Prime Minister
2.
Past Master (of a fraternity)
3.
Paymaster
4.
Postmaster
5.
(military) Provost Marshal

p.m.

abbreviation
1.
(indicating the time period from midday to midnight) post meridiem See a.m.
2.
post-mortem (examination)
Word Origin
(sense 1) Latin: after noon
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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Word Origin and History for Pm

p.m.

abbreviation of Latin post meridiem "after noon."

Online Etymology Dictionary, © 2010 Douglas Harper
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Pm in Medicine

pm abbr.
picometer

Pm
The symbol for the element promethium.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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Pm in Science
Pm  
The symbol for promethium.
promethium
  (prə-mē'thē-əm)   
Symbol Pm
A radioactive metallic element of the lanthanide series. Promethium does not occur in nature but is prepared through the fission of uranium. It has 17 isotopes, one of which is used to make long-lived miniature batteries that work at extreme temperatures for up to five years. The longest-lived isotope, Pm 147, has a half-life of 2.5 years and is used as a source of beta rays. Atomic number 61; melting point 1,168°C; boiling point 2,460°C; valence 3. See Periodic Table.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Pm in Technology


1. preventive maintenance.
2. Presentation Manager
3. ["PM, A System for Polynomial Manipulations", G.E. Collins, CACM 9(8):578-589 (Aug 1966)].
[Jargon File]

networking
The country code for St. Pierre and Miquelon.
(1999-01-27)

The Free On-line Dictionary of Computing, © Denis Howe 2010 http://foldoc.org
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Related Abbreviations for Pm

pm

  1. phase modulated
  2. phase modulation

pM

picomolar

Pm

promethium

PM

  1. particulate matter
  2. past master
  3. police magistrate
  4. postmaster
  5. postmenopausal
  6. postmistress
  7. postmortem
  8. prime minister
  9. private message
  10. provost marshal

pm.

  1. premium
  2. premolar

p.m.

Latin post meridiem (after noon)

P.M.

Latin post meridiem (after noon)
The American Heritage® Abbreviations Dictionary, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Encyclopedia Article for Pm

(Pm), chemical element, only rare-earth metal of transition Group IIIb of the periodic table not detected in nature. Conclusive chemical proof of the existence of promethium, the last of the rare-earth elements to be discovered, was obtained (1947) by J.A. Marinsky, L.E. Glendenin, and C.D. Coryell, who isolated the radioactive isotope promethium-147 (2.7-year half-life) from uranium fission products at the research site at Oak Ridge, Tenn. Identification was firmly established by spectroscopy. Earlier investigators thought that they had found the element with atomic number 61 in naturally occurring rare earths and had prematurely called it illinium and florentium. Promethium-147 is effectively separated from the other rare-earth fission products by an ion-exchange method. Its soft beta radiation is converted to electricity in miniature batteries formed by sandwiching promethium between wafers of a semiconductor such as silicon; these batteries operate in extreme temperatures for five years. Promethium has also been prepared by slow neutron bombardment of the isotope neodymium-146; the resultant isotope, neodymium-147, decays by electron emission to promethium-147. The metal itself was first prepared (1963) by reduction of the fluoride, PmF3, with lithium

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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