exa- [EKS uh] +

(Greek: from hexa-, "six"; a decimal prefix used in the international metric system for measurements)

This is a prefix that is used in the metric [decimal] system as one-quintillion [U.S.] or trillionfold [U.K.], 1018 [1 000 000 000 000 000 000]. The metric symbol for exa- is E.

A unit of information equal to 1000 petabits or 1018 bits.

A bit is a unit of measurement of information (from Binary + digIT); the amount of information in a system having two equiprobable states: "There are eight bits in a byte".

1. A unit of information equal to 1 000 petabytes or 1018 bytes.
2. A unit of information equal to 1 024 pebibytes or 260 bytes.
exagram (Eg)
A unit of mass equal to 1,000,000,000,000,000,000 grams.
A measure of energy, symbol EJ; 1018J, equivalent to 1015 Btu.
exasecond (Es)
The age of the universe is estimated to be 0.4 exasecond (12 billion years).
— Source: Chemistry and Molecular Biology Resources, UC Extension, Berkeley/San Francisco

Related "metric" families: yotta; zetta; peta; tera; giga; mega; kilo; hecto; deka; deci; centi; milli; micro; nano; pico; femto; atto; zepto; yocto.