The story
From the ending -idian, on the model of annelidian, arachnidian, ascidian, etc. By surface analysis, -id + -ian.
Etymology from Wiktionary, CC BY-SA 4.0.
-idian
Today it means: Forming nouns or adjectives. Full definition →
Today it means: Forming nouns or adjectives. Full definition →
From the ending -idian, on the model of annelidian, arachnidian, ascidian, etc. By surface analysis, -id + -ian.
Etymology from Wiktionary, CC BY-SA 4.0.