Hepta-

Hepta- was an old prefix proposed a few years before zetta-.https://en.wikipedia.org/wiki/Unit_prefix It comes from the Greek word meaning 7, as it was the 7th power of 1000. It was later removed and replaced with zetta- beacuse its symbol h was already used as a symbol for hecto-.
The reciprocal of this prefix is septo- from Latin septem meaning 7. It was also dropped and replaced with zepto- because its symbol s was also already used as a symbol.BIPM - Résolution 4 de la 19e CGPM
== Sources ==
Category:Prefixes
Category:Rare prefixes
Category:SI prefixes