The Smile singer admits she was stunned the Royals singer did not get a nod after spending much of 2013 at the top of pop charts around the world.
Lorde did land four major nominations for her hit song and album Pure Heroine, but Allen insists the teen should have had a fifth.
She tweets, "Legendary producer Jimmy Jam, who is chairman emeritus of the Recording Academy, suggested that Lorde's omission was because she, in effect, 'skipped a grade' by having such a successful debut song.
"I guess what defines 'new artist' is 'not yet having a grammy', yes always a new artist until you've won. that makes sense."
Jay Z is the Grammy Award nominations leader with nine. The awards will be handed out on 26 January (14).