The word for “week” in Gnomish Lexicon of the 1910s was G. ochlad. It is related to the word G. odin “seven” and derived from ᴱ✶ot·g’lāta (GL/62), though its exact phonetic development is obscure. Roman Rausch speculated (HPG/2.6) that the [tgl] somehow became [ɣl] (ʒl) and then [ɣl] > [xl] (chl).

Conceptual Development: In a very early list of weekday names, this word appeared as G. oglad (PE14/16, 21), but it was altered to ochlad in the Gnomish Lexicon from the 1910s (GL/62).

Neo-Sindarin: There are no later words for a seven-day week in Noldorin or Sindarin. The closest we come is N. lhevnar for the Valarin five-day week, but this is inappropriate since it is based on the root ᴹ√LEPEN “five”.

The later Sindarin word for “seven” was odog from the root √OTOK. It is difficult but not impossible to produce initial och- from this root. Such a form appeared in S. ochui, a variant of othui “seventh”. This word probably developed from *✶ot’kō-yā > okkōyā > okkhuia > ochui, similar to the development of ✶etkat- > S. echad-. Perhaps ᴺS. ochlad could be derived from primitive *✶ot’k-galáta > okkh’lata > ochlad (“seven shining?”). However, the combination chl does not appear in later Sindarin.

The earlier (replaced) form oglad “week” is more phonetically plausible in Sindarin, since the gl does occur medially. However, this word probably reflects the Gnomish phonetic rule that [dl] became [gl], a rule Tolkien retained in Noldorin but abandoned in Sindarin. So perhaps a more appropriate revised form would be ᴺS. odlad, from *ot(ok)-g’lata > otlata > odlad, analogous to the revision of N. eglenn “exiled” >> S. edlen(n).