Where does “arego” come from?

arego (Esperanto) comes from Esperanto aro, from Esperanto -aro, from Russian -а́рь, from Proto-Slavic -ařь, from Gothic -𐌰𐍂𐌴𐌹𐍃, from Proto-Germanic -ārijaz, from Latin -ārius, from Proto-Italic *-āzios — Forms relational adjectives to nouns (and rarely numerals).

arego (Esperanto): large group, horde, host, drove

Definitions

large group, horde, host, drove

Ancestry of “arego”, step by step

Step	Language	Word	Meaning
1	Esperanto	aro	bunch
2	Esperanto	-aro	a coherent collection for a noun
3	Russian	-а́рь	er, -or
4	Proto-Slavic	-ařь	-er
5	Gothic	-𐌰𐍂𐌴𐌹𐍃	-er
6	Proto-Germanic	-ārijaz	-er
7	Latin	-ārius	er
8	Proto-Italic	*-āzios	Forms relational adjectives to nouns (and rarely numerals)

Every word from Proto-Italic *-āzios →Every word from Latin -ārius →Every word from Esperanto -aro →