Chi

CHI could mean:

Chile, the long and narrow South American nation between the Andes and the Pacific Ocean.
Chicago, the IATA city code for a major US city (sometimes informally written "Chi" or "Chi-town"). Additionally, most Chicago sports teams can be called "CHI" or "Chi" when citing scores, etc.
 Chicago Bears, a National Football League team
 Chicago Blackhawks, a National Hockey League team
 Chicago Bulls, a National Basketball Association team 
 Chicago Cubs, a Major League Baseball team
 Chicago White Sox, a Major League Baseball team
 Child Health International, a UK based charity for children's health (especially Cystic Fibrosis) in poor countries
 Human-Computer Interaction, otherwise known as Computer-Human Interaction (CHI) 
 CHI, an annual, international academic conference on the topic of Computer-Human Interaction
 Chromosomal crossover, in homologous recombination, a viral DNA sequence called a "crossover hotspot instigator" (CHI)
CHI, Longwood University's, secret honorary society formed in 1900 in Farmville, Virginia
 Closed Head Injury, meaning the skull is not broken.
 Columbia Helicopters, Inc of Aurora, Oregon.  Manufacturer and Operator of heavy lift helicopters
 Chingford railway station, London; National Rail station code CHI

 Chi 
Chi could mean:
 Chi, the Greek letter, Χ
 The Chi distribution, which is denoted by 
 The Chi-square distribution, which is denoted by 
Chi (kana), a letter used in the Japanese script Hiragana
 Chi (magazine), an Italian magazine based in Milan
 Chi Cheng (musician), Bassist for Deftones
 Chi McBride, actor
 Chi River in North-East Thailand
 Chi, a fictional character in the anime/manga series Chobits
 In Igbo mythology in Nigeria, Chi is a god or personification of an individual's fate
 Chi is an alleged life force in every thing