A thank offering was a sacrifice given to thank God for his goodness and blessings. It was one type of fellowship offering.
Bible dictionary
Thank Offering
The International Standard Bible Encyclopedia (1915)The classic article on this subjectSmith’s Bible Dictionary (1863)The entry on this subject
Adapted by Mission Mutual (Aquifer Open Bible Dictionary) from Tyndale Open Bible Dictionary © 2023 Tyndale House Publishers. CC BY-SA 4.0. About the sources