Sir is a respectful form of address for a man, and a formal title used in the United Kingdom for knights and baronets. Sir, SIR or SiR may also refer to: Places Iran Sir, Iran, a city in Fars Province Sir, Razavi Khorasan, a village in Razavi Khorasan Province Sir, West Azerbaijan, a village in West Azerbaijan Province West Bank Sir, Jenin, a Palestinian village in Jenin district Sir, Tulkarm, a Palestinian village in Tulkarm district Others Sir Creek, on the border between India and Pakistan People Sir (singer), American singer, songwriter, record producer Jaroslav Šír (born 1923), Czechoslovak former skier József Sir (1912-1996), Hungarian sprinter Sedat Sir (born 1975), Turkish-Australian former Australian Rules footballer Entertainment Sir (1993 film), a Bollywood film Sir (A Series of Unfortunate Events), a fictional character in A Series of Unfortunate Events Sir (album), by Fischerspooner Sir (2018 film), an Indian Hindi-language romantic drama film "Sir", a song by Nicki Minaj from Queen SIR Organizations 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 Mathematics and statistics Sequential 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 Other uses SIR proteins (silent information regulator), in molecular biology 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 South Indian Railway, an early Indian railway company 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 Other uses Sır Dam, on the Ceyhan River in Turkey Sirene (Sir in Serbian), a type of cheese