Any of a group of hydrocarbons that are made up of building blocks of isoprene (C5H8) or similar five-carbon units, with a monoterpene made up of two units (example: limonene and pinene), a sesquiterpene made up of three units (example: humulene, a Hops aromatic), and a diterpene made up of four units. The terpenes, in our context, are the primary constituents in the aromatic fractions of our scented plants.