hi

Definitions

General English

  • interjection showing a greeting
  • adjective not able to hear properly

Astronomy

  • (written as HI)
    Neutral hydrogen in interstellar gas clouds. HI regions are those where most of the hydrogen present is unionised. It can be present either as hydrogen atoms or as molecules of two hydrogen atoms.

Medical

  • acronym forhearing-impaired
    (written as HI)
  • adjective having a degree of hearing loss
http://www.dictionarycentral.com/definition/hi.html