Sir (disambiguation)

Sir is a respectful form of address for a man and a formal title used in the United Kingdom for knights and baronets.

Sir or SIR may also refer to:

Places

Sir (film), a 1993 Bollywood film
Sir (A Series of Unfortunate Events), a Guardian character in A Series of Unfortunate Events

Sigma Iota Rho, a collegiate honour society for international studies
Society of Interventional Radiology, an American organization of health professionals
Sons In Retirement (SIR), a fraternal organization of retired men

Sampling Importance Resampling, in mathematics, a particle filtering algorithm
Signal-to-interference ratio, in telecommunication, the ratio of useful signal versus co-channel interference received
Short interest ratio, a metric signalling prevailing investors' sentiment
SIR model, a compartmental model of the progress of an epidemic

Saskatchewan International Raceway, a Saskatoon drag strip
Security Industry Registry, a corporate service provided by the New South Wales Police Force
Singapore Infantry Regiment, the main formation of the Singapore Army
Sion Airport (IATA code SIR), the airport in Sion, Switzerland
Staten Island Railway, rapid transit line in the borough of Staten Island, New York, United States
Statutory Invention Registration, publication of an invention by the United States Patent and Trademark Office
Surrey Iron Railway, a horse-drawn plateway that linked the former Surrey towns of Wandsworth and Croydon
Serial Infrared, a category of Infrared Data Association
Secondary Image Registration, a type of passive autofocus
Supplemental Inflatable Restraint or airbag, a vehicle safety device