Where does “HR” come from?

HR (Japanese) comes from English homeroom, from English Home, from Middle English hōm, from Old English hām, from Proto-West Germanic haim, from Proto-Germanic haimaz, from Proto-Indo-European ḱóymos, from Proto-Indo-European ḱey- — to be lying down; to settle.

Ancestry of “HR”, step by step

StepLanguageWordMeaning
1EnglishhomeroomA classroom where school pupils of the same age...
2EnglishHomeA key that when pressed causes the cursor to go...
3Middle Englishhōmhome, residence, dwelling
4Old Englishhāmhome; village, community; village, hamlet, manor,...
5Proto-West Germanichaimhome
6Proto-Germanichaimazhome; house; village
7Proto-Indo-Europeanḱóymosof the home, belonging to the family; village,...
8Proto-Indo-Europeanḱey-to be lying down; to settle
Every word from Proto-Indo-European ḱey-Every word from Proto-Indo-European ḱóymosEvery word from Proto-Germanic haimaz