俱舍論記 8.32

8.32

「又欲之界至應知亦然」者，第二解約依主釋。此界是欲之界，故名欲界。即是欲之任持，以此界能任持欲故。界是能持，欲是所持，能、所合論故名欲界。餘二界亦然。

"Furthermore, the realm of desire... should be understood likewise" is the second explanation in terms of the genitive compound (tatpuruṣa). This realm is the realm of desire, hence it is called the desire realm. That is, it is the supporter of desire, because this realm can support desire. The realm is the supporter, and desire is that which is supported; combining the two, it is called the desire realm. The other two realms are likewise.