From WordNet (r) 2.0 (August 2003) [wn]:
sir
n 1: term of address for a man
2: a title used before the name of knight or baronet [syn:
Sir]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Sir \Sir\, n. [OE. sire, F. sire, contr. from the nominative L.
senior an elder, elderly person, compar. of senex,senis, an
aged person; akin to Gr. ??? old, Skr. sana, Goth. sineigs
old, sinista eldest, Ir. & Gael. sean old, W. hen. Cf.
Seignior, Senate, Seneschal, Senior, Senor,
Signor, Sire, Sirrah.]
1. A man of social authority and dignity; a lord; a master; a
gentleman; -- in this sense usually spelled sire. [Obs.]
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He was crowned lord and sire. --Gower.
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In the election of a sir so rare. --Shak.
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2. A title prefixed to the Christian name of a knight or a
baronet.
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Sir Horace Vere, his brother, was the principal in
the active part. --Bacon.
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3. An English rendering of the LAtin Dominus, the academical
title of a bachelor of arts; -- formerly colloquially, and
sometimes contemptuously, applied to the clergy. --Nares.
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Instead of a faithful and painful teacher, they hire
a Sir John, which hath better skill in playing at
tables, or in keeping of a garden, than in God's
word. --Latimer.
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4. A respectful title, used in addressing a man, without
being prefixed to his name; -- used especially in speaking
to elders or superiors; sometimes, also, used in the way
of emphatic formality. "What's that to you, sir?"
--Sheridan.
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Note: Anciently, this title, was often used when a person was
addressed as a man holding a certain office, or
following a certain business. "Sir man of law." "Sir
parish priest." --Chaucer.
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Sir reverance. See under Reverence, n.
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From The Free On-line Dictionary of Computing (19 Sep 2003) [foldoc]:
SIR
1. <language> An early system on the IBM 650.
[Listed in CACM 2(5):16, May 1959].
2. <standard> Serial Infrared. An infrared standard from
IrDA, part of IrDA Data. SIR supports asynchronous
communications at 9600 bps - 115.2 Kbps, at a distance of up
to 1 metre.
[Reference?]
(1999-10-14)