Wiktionary
orsellinic acid
n. (context organic compound English) A phenolic carboxylic acid, ''2,4-dihydroxy-6-methylbenzoic acid'', found in some lichens
Wikipedia
Orsellinic acid
Orsellinic acid, more specifically o-orsellinic acid, is a phenolic acid. It is of importance in the biochemistry of lichens, from which it can be extracted.