-ˌdrēn noun
( -s )
Etymology: New Latin phellandrium + International Scientific Vocabulary -ene
: either of two isomeric aromatic oily liquid terpene hydrocarbons C 10 H 16 occurring in many essential oils:
a. : the terpene C 3 H 7 C 6 H 6 CH 3 occurring in the dextrorotatory form especially in bitter fennel oil and ginger-grass oil and in the levorotatory form especially in eucalyptus oils (as from Eucalyptus phellandra ); 1,5- para -menthadiene — called also alpha-phellandrene
b. : the terpene C 3 H 7 C 6 H 7 = CH 2 occurring in the dextrorotatory form especially in water-fennel oil and in the levorotatory form especially in turpentine; 1(7),2- para -menthadiene — called also beta-phellandrene