מַצָּה matstsâh (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)

1) unleavened (bread, cake), without leaven.

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