Teatrih, Tiheiterich.

(6) With D-t: Dioterih, Diotericus, Diotricus, Deotrich, Deotrih,
Dieterih, Dieterich, Dietrich, Diterih, Ditricus.

(7) With Th-th: Theotherich, Theothirich.

(8) With T-th: deest.

(9) With D-th: Dietherich.

It is quite true that, strictly speaking, the forms with Th-d, are
Low-German, and those with D-t, High-German, but before we trust
ourselves to this division for historical purposes, we must remember
three facts: (1) that Proper Names frequently defy Grimm's Law; (2)
that in High-German MSS. much depends on the locality in which they
are written; (3) that High-German is not in the strict sense of the
word a corruption of Low-German, and, at all events, not, as Grimm
supposed, chronologically posterior to Low-German, but that the two
are parallel dialects, like Doric and Aeolic, the Low-German being
represented by the earliest literary documents, Gothic and Saxon, the
High-German asserting its literary presence later, not much before
the eighth century, but afterwards maintaining its literary and
political supremacy from the time of Charlemagne to the present day.

When Theodoric married Odeflede, the daughter of Childebert, and a
sister of Chlodwig, I have little doubt that, at the court of
Chlodwig or Clovis, his royal brother-in-law was spoken of in
conversation as Dioterih, although in official documents, and in the
history of Gregory of Tours, he appears under his classical name of