The noun homicide means a murder. If you kill another person, you are committing a homicide. The level of the homicide is legally defined as murder if the act was intentional and as manslaughter if it was unintentional.
Remember the meaning of homicide by remembering that cide, from the Latin cida, refers to killing, while the Latin homo means "man.” So homicide means “killing a man.” You can see another example in this quote from Oliver Wendell Holmes: “Life and language are alike sacred. Homicide and verbicide — that is, violent treatment of a word with fatal results to its legitimate meaning, which is its life — are alike forbidden.”
Definitions of homicide
the killing of a human being by another human being
a battle in Montana near the Little Bighorn River between United States cavalry under Custer and several groups of Native Americans (1876); Custer was pursuing Sioux led by Sitting Bull; Custer underestimated the size of the Sioux forces (which were supported by Cheyenne warriors) and was killed along with all his command