Does "grim" share an etymology with the surname "Grimm"?

People have often punned about Grimm's fairy tales being very grim. For example, TV Tropes has the trope Grimmification about tales being made more grim. (The Brothers Grimm didn't engage in Grimmification - they didn't need to. In fact, they Disneyfied.)

Are the two words "grim" and "Grimm" etymologically related?

The English edition of Wiktionary does not have an entry for "Grimm", nor does the Online Etymology Dictionary.

Wiktionary states that grim came from Old English, which came from Germanic. And Grimm is used as a surname in Germany.

Grimm has an entry in the German Wiktionary, but even with Google translate I can't tell if it's talking about a name, a noun, or both.

One person I talked to about this said that "Grimm" meant "hooded", which would explain "The Grim Reaper" (apart from it only have one "m"). Is that true?

Solution 1:

It is clear that Old English grimm is cognate with Ger grimm(ig); Koebler Althochdeutscheswörterbuch) refers this to Pokorny (Indo-European Etymological Dictionary) 458, where it is derived from PIE root *ghrem-2, “heavy sound, thunder, grumble”.

However, Koebler also notes a similar word, grimo, “helmet, mask”, which I imagine is what your informant who suggested “hooded” was referring to; it’s cognate with OE and Icelandic grima, from which Tolkien took the name of the evil counsellor Grima Wormtongue. Pokorny 457 derives these from PIE root *ghrēi-, *ghrəi-, *ghrī-, *ghrei-, “smear”, from which he also derives Middle Low German grimet, “black-streaked”, and grēme “smut”, which appear to be cognate with English grime.

Both roots were used in mediaeval personal names. Genealogical sites derive the modern surname variously from both; but they do not cite authorities and may safely be ignored.

Unless an authority can be found which definitively traces the Brothers' surname, I think the verdict must be Not Proven.

Solution 2:

Well, we once spelled grim with two m’s in English, as grimm. The OED gives the etymology of grim as:

OE. grim(m) = OFris. grim, OS. grim (Dutch grim), OHG. and MHG. grim (G. grimm), ONor. grimmr (Sw. grym harsh, Da. grim ugly). Ormin employs a disyllabic form grimme, corresponding to OHG. grimmi, MHG. grimme. The OTeut. root *grem- is an ablaut-variant of *gram-; see grame a.

So it would seem the same word.

What I find fascinating is the hidden gem that grim is ultimately an ablaut variant of a gram- word, which makes me think of grammar and linguistics, which makes me think of Grimm’s Law.