מַצָּהmatstsâhStrong's H4682

properly, sweetness; concretely, sweet (i.e. not soured or bittered with yeast); specifically, an unfermented cake or loaf, or (elliptically) the festival of Passover (because no leaven was then used)

Derivation: from מָצַץ (H4711) in the sense of greedily devouring for sweetness