In science:

• Homo (genus), the genus of humans (Homo sapiens) and closely related species such as Neanderthals
• HOMO/LUMO, Highest Occupied Molecular Orbital

In dairy:

• An abbreviation for homogenized milk, sometimes used on product packaging

In slang:

• Pejorative slang term for homosexual, directed at homosexual persons or non-homosexual persons for comedic or pejorative effect.

Organizations:

• Swedish Ombudsman against Discrimination on Grounds of Sexual Orientation, short form: HomO

In literature:

• The wolfhound in Victor Hugo's novel The Man Who Laughs