Hello mick
Capsicum is Green pepper or Bell pepper; http://en.wikipedia.org/wiki/Bell_pepper
Mamta
capsicum is the genus which includes all the species of chillies and 'sweet peppers' or 'bell peppers' in the US,and paprikas of Europe.
Commonly, in supermarkets and the like, sweet peppers are often refered to as capsicums, although it could just as correctly be applied to all chillies. This is why it is perfectly acceptable to use ground dry capsicum (sweet pepper), also known as paprika, to 'dilute' the heat of chilli peppers, or used instead of, or as well as, fresh chillies in Indian recipes, to reduce the heat but maintain the colour.