Strong’s Dictionary of Hebrew Words:
Transliteration:
matstsah
Meaning:
from 4711 in the sense of greedily devouring for sweetness; 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)
KJV Usage:
unleaved (bread, cake), without leaven