The Collaborative International Dictionary
Paprika \Pa"pri*ka\, n. Also Paprica \Pa"pri*ca\ [Hung. paprika Turkish pepper; prob. through G.] The dried ripened fruit of Capsicum annuum or various other species of pepper; also, the mildly pungent condiment prepared from it.
Bell pepper \Bell" pep`per\ (Bot.) A species of Capsicum, or Guinea pepper ( Capsicum annuum). It is the red pepper of the gardens.
Capsaicin \Cap*sa"i*cin\, n. [From Capsicum.] (Chem.) A colorless crystalline substance extracted from the Capsicum annuum, and giving off vapors of intense acridity.
Capsicine \Cap"si*cine\, n. [From Capsicum.] (Chem.) A volatile alkaloid extracted from Capsicum annuum or from capsicin.
Capsicum \Cap"si*cum\ (k[a^]p"s[i^]*k[u^]m), n. [NL., fr. L. capsa box, chest.] (Bot.) A genus of plants of many species, producing capsules or dry berries of various forms, which have an exceedingly pungent, biting taste, and when ground form the red or Cayenne pepper of commerce.
Note: The most important species are Capsicum baccatum or bird pepper, Capsicum fastigiatum or chili pepper, Capsicum frutescens or spur pepper, and Capsicum annuum or Guinea pepper, which includes the bell pepper and other common garden varieties. The fruit is much used, both in its green and ripe state, in pickles and in cookery. See Cayenne pepper.
Cayenne \Cay*enne\, n. [From Cayenne, a town and island in French Guiana, South America.] Cayenne pepper. Cayenne pepper.
(Bot.) A species of Capsicum ( Capsicum frutescens) with small and intensely pungent fruit.
A very pungent spice made by drying and grinding the fruits or seeds of several species of the genus Capsicum, esp. Capsicum annuum and Capsicum Frutescens; -- called also red pepper. It is used chiefly as a condiment.
Wikipedia
Capsicum annuum is a species of the plant genus Capsicum native to southern North America and northern South America. This species is the most common and extensively cultivated of the five domesticated capsicums. The species encompasses a wide variety of shapes and sizes of peppers, both mild and hot, ranging from bell peppers to chili peppers. Cultivars are descended from the wild American bird pepper still found in warmer regions of the Americas. In the past some woody forms of this species have been called C. frutescens, but the features that were used to distinguish those forms appear in many populations of C. annuum and there is no consistently recognizable C. frutescens species.