1. Not feeling thankful for favours; showing little or no gratitude; making no returns for culture; unpleasing; unacceptable.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• ujgrateful,
• ungreatful,
• ingratful,
• ingrateful,
• ungreateful,
• ungratefull,
• ungratful,
• ugrateful,
• ungrteful,
• ungraseful,
• yngrateful,
• hngrateful,
• ungratefuly,
• ungratefully,
• ungratifed,
• ingraetful,
• Untesteful,
• un gratefull,
• unfatefull,
• ungrasful

• ungreased,
• ungracefully,
• ungrasped,
• ungratefully,
• uncreased,
• uncrate,
• ungratified,
• ungraceful.

The adjective form of the word "ungrateful" is "ungrateful".