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 pollinated and therefore does not develop seeds, increasing the concentration of cannabinoids and terpenes. This cultivation technique was developed in Sinaloa, Mexico, in the 1970s, by the drug trafficker Rafael Caro Quintero 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 recreational purposes 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, of up to 34% THC content. The expression sinsemilla is practically obsolete since feminized seeds emerged in the 1990s. Feminized seeds are the outcome of a process entailing hormonally induced self-pollination of female cannabis plants, typically by silver ions.