Antonyms of adj thankful

1 sense of thankful

Sense 1
grateful (vs. ungrateful), thankful -- (feeling or showing gratitude; "a grateful heart"; "grateful for the tree's shade"; "a thankful smile")


Similarity of adj thankful

1 sense of thankful

Sense 1
grateful (vs. ungrateful), thankful -- (feeling or showing gratitude; "a grateful heart"; "grateful for the tree's shade"; "a thankful smile")
       => appreciative -- (feeling or expressive of gratitude; "was appreciative of his efforts"; "an appreciative word")
       => glad -- (feeling happy appreciation; "glad of the fire's warmth")