grateful
adj.
1550s, "pleasing to the mind," also "full of gratitude," from obsolete adj. grate "agreeable, thankful," from Latin gratus "pleasing" (see grace, n.). "A most unusual formation" [Weekley]. Hard to think of another case where English uses -ful to make an adjective from an adjective. Related: Gratefully; gratefulness.
〔李〕[grat=pleasing, thankful令人高兴的，感谢的；-e-;-ful a.=having the quality有……性质的→] a.① pleasing, or causing pleasure令人愉快的；可喜的