[From Middle English ingrat, ungrateful, from Old French, from Latin ingrātus : in-, not; see in-1 + grātus, pleasing, thankful; see gwerə-2 in Indo-European roots.]
1393, originally an adj. meaning "unfriendly," from L. ingratus "unpleasant, ungrateful," from in- "not" + gratus "pleasing, beloved, dear, agreeable" (see grace). The noun meaning "ungrateful person" dates from 1672.
(ĭn'grāt') 
greɪt