Cryogenics scale, both of which measure from absolute zero, rather than more usual scales such as Celsius or Fahrenheit, with their zeroes at arbitrary temperatures. The word "cryogenics" stems from Greek "κρύο (cryo)" – "cold" + "γονική (genic)" – "having to do with production". Cryogenic fluids with their boiling point in Kelvin Liquefied gases, such as liquid nitrogen and liquid helium, are used in many cryogenic applications. Liquid nitrogen is the most commonly used element in cryogenics and is legally purchasable around the world. Liquid helium is also commonly used and allows for the lowest attainable temperatures to be reached. These
Prefix forms may or may not qualify for inclusion in such a list. This list takes the broad view that "acro-" and "auto-" count as English derivational prefixes because they function the same way that prefixes such as "over-" and "self-" do. As for numeral prefixes, only the most common members of that class are included here. There is a large separate table covering them all at Numeral prefix > Table of number prefixes in English. The choice between hyphenation or solid styling for prefixes in English is covered at Hyphen > Prefixes and suffixes. The most commonly used prefix in