What is "thiolactone"

n. (context organic chemistry English) Any of a class of compounds formally derived from the lactones by replacing either, or both, of the oxygen atoms with sulfur

Thiolactones are a class of heterocyclic compounds in organic chemistry. They are analogs of the more common lactones in which an oxygen atom is replaced with a sulfur atom. The sulfur atom is within the ring system and adjacent to a carbonyl group.