Initialism of hot dry rock.abbreviation,alt-of,countable,initialism,uncountable
Initialism of humanitarian daily ration.abbreviation,alt-of,countable,initialism,uncountable
Initialism of high dynamic range.abbreviation,alt-of,countable,initialism,uncountable
Initialism of hard disk recorder or hard drive recorder (“a recording device that records onto a hard disk drive”).abbreviation,alt-of,countable,initialism,uncountable