Cannabis sinsemilla (Spanish pronunciation: [sinseˈmiʝa]) also known as sensimilla, sinse or sensi (can be translated into English as seedless cannabis) is the female Cannabis plant that has not been fertilized and therefore does not develop seeds, increasing the density of cannabinoids and terpenes. This cultivation technique emerged in Michoacán, Mexico, in the 1970s and consists of separating male plants as soon as they are known to be male, in order to avoid pollination of female pistils. The seeds are not useful for humans, and require the plant to make a great expenditure of energy that could be invested in increasing the tetrahydrocannabinol (THC) of the inflorescences (buds).
The technique became popular in the United States as sinsemilla, sinsemilia, sinse, or sense. In 1980, an American study indicated that the average THC of street marijuana was 1.8%, while sinsemilla reached 6%. Sinsemilla cannabis is a cultivation technique, so it should not be confused with skunk, which refers to strains with a high percentage of THC. The expression sinsemilla is practically obsolete since feminized seeds emerged in the 1990s, genetically modified seeds to always sprout females.