Anyone who is planning to read it fairly soon is likewise excused on account of spoilers, though spoilers for infodump sections of a fifteen-year-old book is a bit of a silly proposition.
In the Alliance/Union universe, technology has gotten to the point where most schooled learning is done by means of automated instruction. The automated instruction uses a combination of video and audio input, blood chemical manipulation, and direct electrical muscle stimulation, under smart computer control, and often designed to interact specifically with previous instruction, and geared toward the learning strengths of the student. This learning tool is called "tape". (But wait! There's more!)
Technology has also reached the point where they can clone and engineer humans. Naturally, someone tried taking shortcuts in the process of childrearing in a particular low-population crunch, by means of putting not just informational schooling, but important parts of the childrearing process on tape, augmented with human affection. The humans that result from this process were ... odd: highly skilled in their areas of expertise, but not accustomed to moral grey areas or certain kinds of innovation. They are called "azi". By the time the book has properly begun, they are being deliberately created, with instruction tailored to their genetically predisposed strengths. (Normally-raised humans are citizens, "CIT" for short.) (And oh yes, the society has a whole *bundle* of problems -- azi are well-treated but not free until they get their Final tape (giving them permission to become self-directing & Contracting them to themselves, from what I figure; there never are really details), CITs have bags and bags of crazy, an azi who writes their own programming is not entirely sane, a CIT doing the same is societally accepted but probably also crazy, and let us not get into Resune Our Benevolent Overlords.)
There is tape for schooling both basic and specific, tape for entertainment, tape for counseling and psychiatry, tape for affirming an azi's self-esteem and most baseline values. This is not just "tape" but "my tape".
I read this book young. I'm glad that I read it when I did, because I wouldn't be the same person I am today had I not.
There are, in my life, certain formative books that resonate strongly with my deepest values, in part because they helped build those values. (A person who was raised Christian might have this reaction to the Bible and other common Christian sourcebooks. Our parents did not press religion on us, and there don't seem to be many sources of organized religion that don't also make me feel like fleeing. So that's out.) The first two books on my list are Cyteen and Spock's World. This is how your mind works. This is what is important. Never lose sight of these things.
If I'm lost, or floundering, back I go to my tape, seeking understanding and reinforcement of my core values. This is me. This is mine.
bad tape: Personality-programming, inflicted from an external source, that is actually very not good. Roughly similar to "toxic memes". (Same source as the above.)
eetee, eetee logic, eetees in [the] mental basement: Insane. Also same source as the above. As opposed to bad tape, this is home-grown madness, built from inputs that may have been perfectly rational when they came in, but allowed to simmer unchecked by any earth logic. Compare "insane troll logic".
man'chi: Again from C.J. Cherryh's books, but from the Foreigner series, on the other side of old Earth. (This is pretty vague as far as plotwise-spoilers go; this stuff is mostly from the scenario-setting and worldbuilding.)
Colonists went out from Earth and got lost. A good portion of them ended up on a planet already populated by its rightful residents, the very alien but somewhat too-close-for-comfort atevi. Human concepts like "love", "trust", "friendship", "filial piety" -- all unknown to atevi -- and in turn, the biologically-driven atevi familial, emotional and ethical bond of man'chi is similarly foreign to humans.
It's like love. It's like loyalty. It's like the bonds of trust and command that one sees in the better Stargate fics. Man'chi flows up through the social hierarchy to the aiji, the leader, who feels no compulsion of higher loyalty, but collects followers and treats their man'chi with respect and protection.
It's a handy word to describe, quickly, to my fellow fen, certain relationships and scenarios that otherwise defy proper description.
Senior: From Diane Duane's Young Wizards series. Wizards in this series are somewhat informally ranked. Someone who is a Senior, or acting as a Senior, is in at least a vague supervisory/advisory capacity over their more junior wizards.
Adopting things wholesale from fantasy doesn't always work well in pagan circles, particularly when applied large-scale, but this one works all right as a shorthand to describe the relationship between two people, one of whom is somewhat more experienced than the other, who is sometimes giving out advice based on that experience, but is not actually a full-time supervisor-in-faith the way that might be implied with titles such as High Priestess or what-have-you.
c'thia: From Spock's World, a Vulcan word, meaning "reality-truth": that which is, without any spin or pussyfooting or lies.