Rnn.
/ˌɑːrˈɛn/, U.S. /ˌɑrˈɛn/ Chemistry.
The element radon.
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1923 Rep. Internat. Comm. Chem. Elem. (I.U.P.A.C.) in Jrnl. Amer. Chem. Soc. 45 870 The three radioactive emanations have been given the names radon, actinon and thoron, with the symbols Rn, An, Tn, to suggest both their origin and their chemical character as members of the family of the rare gases.
1931 Rev. Mod. Physics 3 432 Mache Unit (M.E.) is a concentration unit referred to the Rn content of 1 liter of water or gas, etc.
1965 C. S. G. Phillips & R. J. P. Williams Inorg. Chem. I. xii. 445 Fluorides of Kr, Xe, and Rn have now been discovered.
1988 D. B. J. Easton et al. tr. C. Keller Radiochem. x. 194 The half-lives of the radon isotopes in the two series are different (t½ values for 222Rn and 219Rn are 3·8 d and 4·0 s respectively).
This is a new entry (OED Third Edition, June 2010; most recently modified version published online March 2022).
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RN
RN n. Registered Nurse.
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the world > health and disease > healing > healer > nurse > [noun] > registered nurse
registered nurse1876
State Registered Nurse1903
RN1904
RGN1922
S.R.N.1922
1904 Amer. Jrnl. Nursing 4 408 Any woman who not being certified under this act..who shall take or use the name or title of registered nurse or the abbreviation R.N...shall be liable on summary conviction to a fine.
1973 Parade 18 Feb. 8/1 Incoming patients are evaluated by an RN as to their degree of urgency, and sent to the appropriate area.
1995 Nursing Times 22 Mar. 7/3 RNs who blow the whistle on poor standards of care risk punitive measures from managers.
RN
RN n. Royal Navy.
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society > armed hostility > hostilities at sea > navy > [noun] > the British navy
the king's (also queen's) navya1382
Royal Navy1583
the navy royal1601
the fleet1712
RN?1791
the senior service1899
silent service1904
?1791 Addr. to Public (Soc. Improvem. Naval Archit.) Index 9 Bentinck, William, Esq; R. N. viz. Royal Navy.
1819 Trans. Soc. Arts 37 110 The Gold Medal of the Society was this Session voted to Mr. Thomas Cook, Lieut. R.N. for a Life Raft.
1946 ‘Tackline’ You met such Nice Girls xiii. 144 It is very strange..why R.N. officers are so much meaner with their clothing-coupons than R.N.V.R. officers.
2000 Guardian (Nexis) 17 Nov. 28 After four years in the RN, his long-running stomach ulcer saw him invalided out.
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n.1923as lemmas