exa
exa — prefix
1. added to the front of a unit of measurement (such as the metre, gram, or watt) t
added to the front of a unit of measurement (such as the metre, gram, or watt) to mean 10^18 (one quintillion) times that unit — for example, an exametre is one quintillion metres, a distance used in astronomy for objects far beyond our solar system.
Evelyn learnt in class that one exametre equals a quintillion metres, or about 110 light-years.
exa- + metre → measurement of astronomical distance
The Sun releases roughly 400 exawatts of energy each second into the surrounding solar system.
exa- + watt → stellar-scale power unit
Geologists at the site estimated the upper mantle at over 800 exagrams of rock.
Nila checked the SI prefix table: exa- comes after peta- and means a thousand-fold increase.
Ada's physics report calculated a pulsar's frequency at 30 exahertz, beyond any radio wave humans can detect.
- yocto-
the SI prefix for 10^-24, representing an unimaginably tiny scale at the opposite extreme from exa-
文法句型
exa- + [unit of measurement] → noun (e.g. exametre, exagram, exawatt)
用法筆記
The prefix exa- appears almost exclusively in specialist scientific writing (astronomy, geology, particle physics). In everyday conversation, people do not use exametres or exagrams. It forms nouns only — never adjectives.
常見錯誤
❗ 'The lake holds ten exagrams of water.' ✅ 'The Pacific Ocean holds about 700 exagrams of water.' — exa- quantities are astronomically large; they almost never apply to everyday objects or locations.
2. used with terms for data storage or computing speed (byte, flop, bit) to mean on
used with terms for data storage or computing speed (byte, flop, bit) to mean one quintillion (10^18) units — for example, an exabyte is a quintillion bytes of data, roughly the amount of internet traffic the world sends each month.
Walid backed up the company's servers, which held nearly two exabytes of customer data.
exa- + byte → large data-storage unit
Sumin's team built a supercomputer that runs at one exaflop for typhoon weather modelling.
exa- + flop → computing speed unit
Global video streaming alone now generates over three exabytes of internet traffic every single month.
Pedro read that the Large Hadron Collider produces 30 exabytes of data each year for physicists to study.
Elena's lab stores genome sequences in a database that will reach one exabyte by next spring.
文法句型
exa- + [computing noun] → noun (e.g. exabyte, exaflop, exabit)
用法筆記
The computing sense is more common than the scientific one in everyday media, especially in technology news about data centres and supercomputers. Note that exabyte can refer to either 10^18 bytes (decimal) or 2^60 bytes (binary), depending on the operating system or standard being used.
常見錯誤
❗ 'My new laptop has an exabyte hard drive.' ✅ 'The cloud data centre stores over two exabytes of backup files.' — exa-scale storage exists only in massive data centres and scientific facilities, not in personal devices.