Numerical prefixes are usually derived from the words for numbers in various languages, most commonly Greek and Latin, although this isn't necessarily the case. They occur in 19th, 20th and 21st century coinages, mainly the terms that are used in relation to or that are the names of technological innovations, such as and . They occur in constructed words such as systematic names. Systematic names use numerical prefixes derived from Greek, with one principal exception, . They occur as prefixes… (More on Tri-)