Ilk. genitive grammar.
There are a few attested genitive inflections of Ilkorin words in The Etymologies, most of them as elements in compounds. The singular genitive inflections end in the suffix -a and the plural inflections in -ion. Based on the example Dor. naugol → naugla (Ety/NAUK), it seems the genitive suffix could cause vowel loss (syncope) just as with plural nouns. Based on the example Ilk. thorn → thurnion (Ety/THOR), the genitive plural could also cause i-affection in the Ilkorin dialect like plural nouns as well, though not in the Doriathrin dialect: Dor. than → thanion (LR/405).
The genitive inflection itself is attested as -a(n) (Ety/NAUK). According to that entry, the genitive generally preceded the modified noun in the Doriathrin dialect. This rule may have only applied to that dialect, since there are several counter-examples in general Ilkorin: Ilk. Tor Tinduma and Ilk. Torthurnion. The form -a(n) hints that the genitive might sometimes be expressed with the suffix -n, perhaps after nouns ending in a vowel. If so, this would make the Ilkorin genitive inflection almost the same as the earlier Gnomish genitive, which used -a/-ion after nouns ending in consonants and -n/-thon after nouns ending in vowels (GG/10).
|Dor. Naugla||← naugol||⇒ Nauglamîr||✧ Ety/NAUK|
|Dor. Golda||← (n)gold||⇒ Goldamir||✧ Ety/ÑGOLOD|
|Ilk. Tinduma||“Twilight”||[← tindum]||⇒ Tor Tinduma||✧ Ety/THIN|
|Ilk. Gwethion||[← gwath]||plural||⇒ Urthin Gwethion||✧ EtyAC/WATH|
|Dor. region||← regin (plural)||plural||⇒ Region||✧ Ety/ERÉK|
|Ilk. thonion||“of pines”||← thōn||plural||⇒ Dor-thonion||✧ Ety/THŌN|
|Dor. thanion||“of pines”||← than||plural||⇒ Dorthanion||✧ LR/405|
|Ilk. #thurnion||“of Eagles”||← thorn||plural||⇒ Torthurnion||✧ Ety/THOR|