: a group of nine
To the ancients, nine was a very special number, one often associated with gods and divinity. Legends and literature have long characterized groups of nine as having a special, in some cases magical, significance. Ancient Egyptians organized their gods into groups of nine; even today, their principal group of gods (headed by sun god Re-Atum) is called the "Great Ennead of Heliopolis." The "Ennead" English speakers use in that name traces to "ennea," the Greek word for "nine." "Ennead" is also used generally to refer to other groups of ancient gods. Furthermore, it is the name given to six sets of nine treatises by Greek philosopher Plotinus that were collected and organized by his 3rd-century disciple, Porphyry.
• Usage Nuances from M-W: onerous \AH-nuh-russ\
1 : involving, imposing, or constituting a burden : troublesome
2 : having legal obligations that outweigh the advantages
"Onerous," "burdensome," "oppressive," and "exacting" all refer to something which imposes a hardship of some kind. "Onerous" stresses a sense of laboriousness and heaviness, especially because something is distasteful ("the onerous task of cleaning up the mess fell to the lowest-ranked member")."Burdensome" suggests something which causes mental as well as physical strain ("the burdensome responsibilities of being a supervisor tired her out"). "Oppressive" implies extreme harshness or severity in what is imposed ("the oppressive tyranny of a police state takes its toll upon the residents"). "Exacting" suggests rigor or sternness rather than tyranny or injustice in the demands made or in the one demanding ("the exacting employer required great attention to detail, but rewarded it well").
• Previous E.T.