plu·to·ni·um 
(pl-tōnē-əm)
(pl-tōnē-əm)n. Symbol Pu
A radioactive, silvery, metallic transuranic element, occurring in uranium ores and produced artificially by neutron bombardment of uranium. Its longest-lived isotope is Pu-244 with a half-life of 80 million years. It is a radiological poison, specifically absorbed by bone marrow, and is used, especially the highly fissionable isotope Pu-239, as a reactor fuel and in nuclear weapons. Atomic number 94; melting point 640°C; boiling point 3,228°C; specific gravity 19.84 (25°C); valence 3, 4, 5, 6. See Periodic Table.
[After the dwarf planet PLUTO (from the fact that it follows neptunium in the periodic table).]
- put an end a stop to
- put an end halt stop to
- put aside
- putative
- putatively
- put away
- put by
- put cards on the table
- put down
- putdown
- put-down
- putdownable
- put down roots
- put finger on
- put finger on
- put foot down
- put foot in mouth
- put foot in one's mouth
- put forth
- put forward
- put/have all (one's) eggs in one basket
- put heads together
- put house in order
- put in
- Putin