Where does “ար-” come from?

ար- (Old Armenian) comes from Old Armenian եհար-, from Proto-Indo-European h₁ésh₂r̥ — blood.

Ancestry of “ար-”, step by step

StepLanguageWordMeaning
1Old Armenianեհար-—
2Proto-Indo-Europeanh₁ésh₂r̥blood
Every word from Proto-Indo-European h₁ésh₂r̥ →Every word from Old Armenian եհար- →