Lyrics to Whoville song

In the 1966 Chuck Jones animated version of “How the Grinch Stole Christmas,” those cute little Who’s are heard singing a Christmas song, only some of whose lyrics are intelligible.

I can get the part about “Welcome Christmas, bring your light,” but just what the hell do they mean by “dah-who-dore-iss”??? Let alone “dah-who-dah-moose” and “rah-who-rah-moose”! Am I mishearing the lyrics? Or did the esteemed Dr. Geisel mean something deeper? Do you know if he ever explained it to any of his confidants? Please, please tell me before I die of curiosity!

Scroll down this page. I found this in google by doing a search on grinch song lyrics