Those sweeteners that contain few to no calories but have a higher intensity of sweetness per gram.
There are 6 of them authorized as additives both in North America (by the FDA and Health Canada) and Europe (by the EFSA): saccharin, aspartame, acesulfame potassium, sucralose, neotame, and advantame.
Besides, there are 3 more generally recognized as safe: certain steviol glycosides from the stevia plant, extracts from monk fruit, and thaumatin.
Although authorized in Europe and many other countries, cyclamate remains banned in the US.
Synonyms:
high-intensity sweeteners, non-nutritive sweeteners, non-sugar sweeteners, sugar-free sweeteners