From WordNet (r) 3.0 (2006) [wn]:
porridge
n 1: soft food made by boiling oatmeal or other meal or legumes
in water or milk until thick
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Porridge \Por"ridge\, n. [Probably corrupted fr. pottage; perh.
influenced by OE. porree a kind of pottage, OF. porr['e]e,
fr. L. porrum, porrus, leek. See Pottage, and cf.
Porringer.]
A food made by boiling some leguminous or farinaceous
substance, or the meal of it, in water or in milk, making of
broth or thin pudding; as, barley porridge, milk porridge,
bean porridge, etc.
[1913 Webster]