Hat

Some disjointed facts:

Kuhn connects Germanic 'hat' and 'hood' (NWBlock a/o-alternation) to
Latin 'cassis' "helmet", (-tt-/-ss- alternation, also in Chatti/Hessen).

from 'An essay on substrate studies and the origin of Saami'
"
There are relatively many North Saami names of mountains and uplands
which show the toponym formant -ir ~ -Vr, in a couple of cases
followed by another formant -Vs. In contrast, the same formant is rare
in other types of names (but cf Áigir, a heath (Lea) - the similarity
to áigi 'time' is obviously coincidental). Because in almost every
case the base of the name is etymologically obscure, it is likely that
-ir reflects a substrate language morpheme or lexeme with the meaning
'mountain', 'uplands', or the like.
...
The assumption of substrate origin of the formant -ir is further
supported by the fact that it attaches to the recurring substrate
bases skiehc^(c^)-,jeahk(k)- and nuss- which appear to be semantically
analyzable (see below).
It is conceivable that the name Háhttir may derive from the
Scandinavian loanword háhtta 'hat'. The shape associative mountain
name type Hatten ('the hat') is relatively common in Norwegian
(Sandnes/Stemshaug 1997 s.v, Hatten, cf. s.v. Háhttir), and even Saami
names such as Háhttavárri ('hat-mountain') are occasionally attested.
On the other hand, a formation of the type háhttir < háhtta cannot be
explained as a regular derivative in Saami. There are two
possibilities: either the form Háhttir has been formed from háhtta
'hat' on the analogy of other mountain names ending in -ir, or the
correspondence is coincidental.
"

Bent Jørgensen: Stednavneordbog
"
Hatterrev Kattegat. 1568 Hattes reff. FL snarest sb. hat, EL sb. rev.
"Det hatteformede rev". Sydøst for Hatterrev ligger Hatter Barn, ...
[The -er suffix is anomalous in Danish]
...
Kassebølle Lang. 1426 Kasebølæ. FL sb. glda. kasi 'dynge' [heap].
...
Kassø Åh. 1436 Casse. [no less than 69 mounds in this parish]
...
Kastbjerg Djur., Rand. *1334 Kasbiergh (Rand.), 1442 Kasebregh
(Rand.), 1455 Kasebiærgh (Djur.). FL snarest sb. kase 'dynge [heap],
opdynget bunke (især af møg, affald)' , ...[corresponding to?] Sw.
vårdkas 'varde, bavn' [beacon],
"

Kuhn assigned *katt-/*kass- to a Germanic substrate, which then might
be the same as the Saami substrate (or related). But why h-, then,
unless the Germani on arriving in Scandinavia changed the ka- of a
recognizable cognate to ha-?


Torsten