Wiktionary
tiglic acid
n. (context organic chemistry English) A monocarboxylic unsaturated organic acid, the trans-form of angelic acid, found in croton oil and in several other natural products.
Wikipedia
Tiglic acid
Tiglic acid is a monocarboxylic unsaturated organic acid. It is found in croton oil and in several other natural products. It was also isolated from the defensive secretion of certain beetles.