HI or Hi may refer to:
Hillary Diane Rodham Clinton (; born October 26, 1947) is an American politician who was the First Lady of the United States from 1993 to 2001, U.S.
Human immunodeficiency virus infection and acquired immune deficiency syndrome (HIV/AIDS) is a spectrum of conditions caused by infection with the human immunodeficiency virus (HIV).
Hindi (Devanagari: हिन्दी, IAST: Hindī), or Modern Standard Hindi (Devanagari: मानक हिन्दी, IAST: Mānak Hindī) is a standardised and Sanskritised register of the Hindustani language.
The date of the start of the history of the United States is a subject of debate among historians. Older textbooks start with the arrival of Christopher Columbus on October 12, 1492 and emphasize the European background of the colonization of the Americas, or they start around 1600 and emphasize the American frontier.
High-speed rail is a type of rail transport that operates significantly faster than traditional rail traffic, using an integrated system of specialized rolling stock and dedicated tracks.
The Higgs boson is an elementary particle in the Standard Model of particle physics. First suspected to exist in the 1960s, it is the quantum excitation of the Higgs field, a fundamental field of crucial importance to particle physics theory.