HL

HL is an abbreviation for:

*Half-life (radioactive decay)
*"Half-Life (series)", a video game series
**"Half-Life", the first game in that series
*Hangars Liquides, an electronic music label
*Headline
* a condition of congruence in right angles
*Hectolitre, 100 liters
*Herman Li, Guitarist for the power metal band DragonForce
*"Higher Level", a level of course difficulty in the International Baccalaureate Diploma Programme
*Hit list
*Hitachi-LG Data Storage (also abbreviated HL-DL-ST), a joint venture between Hitachi and LG, mainly producing optical disc drive.
*Hotline
*House of Lords
*Hovedstadens Lokalbaner, a Danish local railway company
*South Korea (amateur radio call sign prefix assigned to the country)
*Horseland

Hl is abbreviation for:

*Hydrogen line