There are no attestations of Hnoss in The Poetic Edda.
Chapter 34-35(p.29): Hnoss is introduced as the daughter of Freyja and Od. Her name is so beautiful that it becomes the word for "treasure" (hnossir).
Freyia is highest in rank next to Frigg. She was married to someone called Od. Hnoss is the name of their daughter. She is so beautiful that from her name whatever is beautiful and precious is called hnossir [treasures].
Chapter 18-22(p.86): A kenning for Freyja is "mother of Hnoss".
How shall Freyia be referred to? By calling her daughter of Niord, sister of Freyr, wife of Od, mother of Hnoss...
Chapter 36-37(p.98): Freyja is referred to by the kenning "Hnoss's mother". In a verse, "Hnoss" is used as a kenning for treasure, and she is also called "Freyr's niece" and the "child of Niord's daughter".
And in this poem Einar has further referred to Freyia by calling her Hnoss’s mother...
I am able to possess Horn’s [Freyia’s] gold-wrapped glorious child [Hnoss; hnoss = treasure]. We received a valuable treasure. Ocean’s fire [gold] rests on shield’s damager [axe], Freyr’s niece [Hnoss] bears her mother’s eyelashrain [tears].
The ruler’s helpful protection was all offered to me. This was close to the sea-hall. I praise highly this child of Niord’s daughter [Hnoss].
Chapter 37-39(p.99): "Hnoss" is used in a kenning, meaning "treasure," given by a warrior.
The battle-gallant urger [warrior] of Vafud’s [Odin’s] assembly [battle] who achieves doughtiness gave me a mighty Van-bride’s [Freyia’s] daughter [Hnoss].
Chapter 75(p.157): Hnoss is named in a list of the Asyniur, and also explicitly as one of Freyja's two daughters.
Hlin and Nanna, Hnoss, Rind and Siofn, Sol and Saga, Sigyn and Vor.
Freyia also wept gold for Od. Her names are Horn, Thrungva, Syr, Skialf and Gefn, and likewise Mardoll. Her daughters are Hnoss and Gersemi.
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