This word is indeclinable, according to the Etymologies
Noldorin
coe
noun. earth
Changes
cíw→ coe ✧ Ety/KEMCognates
- ᴹQ. kemen “soil, earth; Great Lands” ✧ Ety/KEM
Derivations
Phonetic Developments
Development Stages Sources ᴹ√KEM > coe [kǣm] > [kaim] > [kai] > [koe] ✧ Ety/KEM ᴹ✶kēm > cíw [kēm] > [kīm] > [kīv] > [kīw] ✧ EtyAC/KEM Variations
- cíw ✧ EtyAC/KEM (
cíw)
coe
noun. earth
amar
noun. earth
amar
noun. Earth
Cognates
- ᴹQ. Ambar “Earth, World” ✧ Ety/MBAR
Derivations
Element in
Phonetic Developments
Development Stages Sources ᴹ√MBAR > ambar > amar [ambar] > [ambar] > [ammar] > [amar] ✧ Ety/MBAR
ambar
noun. earth
caw
noun. top
caw
noun. top
Derivations
- ᴹ√KAS “head” ✧ Ety/KAS
Phonetic Developments
Development Stages Sources ᴹ√KAS > caw [kāsa] > [kǭsa] > [kǭha] > [kouha] > [kauha] > [kauh] > [kau] ✧ Ety/KAS
An indeclinable word given as {cíw >>} coe “earth” in The Etymologies of the 1930s as a derivative of the root ᴹ√KEM (Ety/KEM; EtyAC/KEM).
Possible Etymology: The primitive form of rejected cíw is given as ᴹ✶kēm and its derivation is clear: the long ē became ī and then the final m reduced to w after i as usual. The derivation of coe is more obscure, however. The likeliest explanation is that Tolkien imagined its ancient form with a slightly lowered vowel which he generally represented as ǣ in this period (in later writings as ę̄). According to the first version of the Tengwesta Qenderinwa and Comparative Vowel Tables from the 1930s (PE18/46; PE19/25), ǣ > ei > ai > ae, and in The Etymologies itself, it seems ai often became oe instead of ae.
Neo-Sindarin: Updating the derivation of hypothetical ✱kę̄m would produced ᴺS. cae in Sindarin phonology. But given the obscurity of its derivation, I recommend using 1950s S. ceven for “earth” instead.