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acrylic
acrylic acid
acrylic resin
acrylonitrile
ACT
act
act of contrition
act of faith
act of God
Act of Union
act on
act out
ACT-UP
act up
Actaeon
ACTH
actin
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actinium
ac·tin·i·um [ ak tínnee əm ]


noun 
Definition:
 
radioactive element: a radioactive silvery white metallic element. Source: pitchblende. Use: source of alpha rays.
Symbol  Ac
[Early 20th century. < Greek aktin- "ray"]
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