hoaryoudaoicibaDictYouDict[hoar 词源字典]
hoar: [OE] Hoar now survives mainly in hoary, a disparaging term for ‘old’, and hoarfrost, literally ‘white frost’. Between them, they encapsulate the meaning of hoar – ‘greyishwhite haired with age’. But it is the colour that is historically primary, not the age. The word goes back to an Indo-European *koi-, whose other descendants include German heiter ‘bright’ and Russian ser’iy ‘grey’.

Another Germanic offshoot was *khairaz – but here the association between ‘grey hair’ and ‘age, venerability’ began to cloud the issue. For while English took the word purely as a colour term, German and Dutch have turned it into a title of respect, originally for an elderly man, now for any man: herr and mijnheer respectively.
=> hare, herring[hoar etymology, hoar origin, 英语词源]
hoar (adj.)youdaoicibaDictYouDict
Old English har "hoary, gray, venerable, old," the connecting notion being gray hair, from Proto-Germanic *haira (cognates: Old Norse harr "gray-haired, old," Old Saxon, Old High German her "distinguished, noble, glorious," German hehr), from PIE *kei-, source of color adjectives (see hue (n.1)). German also uses the word as a title of respect, in Herr. Of frost, it is recorded in Old English, perhaps expressing the resemblance of the white feathers of frost to an old man's beard. Used as an attribute of boundary stones in Anglo-Saxon, perhaps in reference to being gray with lichens, hence its appearance in place-names.