HCL
- HC Lugano
- HCI (disambiguation)
- HCL color space
- HCLTech
- Hairy cell leukemia
- Hardware compatibility list
- Harvard College Library
- Harvard Cyclotron Laboratory
- HashiCorp
- Hennepin County Library
- Hindustan Cables Limited
- Hollow-cathode lamp
- Honolulu Control Facility
- Horizon Coach Lines
- Hydrochloric acid
- Hydrochloride
- Hydrogen chloride
- Hypomania Checklist
- Terraform (software)