Hoar (pronounced hawr or hohr)- In short, the surname ‘Hoar’ can mean ‘one with white or grey hair’ or it can be used to describe particularly heavy, or ‘black’ frost. For a slightly longer explanation, I’ll have to refer you to this paragraph:
Lexicographers have two opinions as to the meaning of the family name. Like most other family names its origin is traced to some common word of the language of the time. According to the theory adopted by the genealogists of the family in England, the name came through the Norman French, from the ancient French and Latin and was derived from a root common to the Latin word “hora.” meaning originally a boundary or mark. As an “hora” or “hour” was a boundary mark on the sun dials formerly exclusively used to measure time, so was “hoar-stone” a designation anciently of memorial marks and boundary stones. Because such boundary stones became in time gray-headed with antiquity, the word acquired a secondary meaning of white or gray. The better lexicographers say that the word “hoar” as used in the expression “hoary head” and “hoar frost” is derived from the
Anglo-Saxon and early Scandinavian root “hor” meaning white or gray. Inasmuch as the name in its present application certainly came to England from Normandy, and as the Norman fighting men of that time were themselves, Northmen or of Scandinavian or northern descent, it would see, probable that the lexicographers have the better of the argument, although it may well be true and is consistent with both theories that the Latin word and the Scandinavian, or northern word, are both derived from an older Amoric or Aryan root having the same basic meaning and perhaps the same genesis.
With thanks to Norton T Horr, who no doubt has to stand up for his surname every now and again, too.