gratiarum actio is 'thanksgiving'; dies (festus) gratiarum actionis is 'Thanksgiving Day'.
What is thanks be to God in Latin?
Deo gratias (Latin for "thanks [be] to God") is a response in the Latin Mass, derived from the Vulgate text of 1 Corinthians 15:57 and 2 Corinthians 2:14.
What are the Latin words of gratitude?
Gratitude, which rhymes with "attitude," comes from the Latin word gratus, which means "thankful, pleasing." When you feel gratitude, you're pleased by what someone did for you and also pleased by the results.