Et In Arcadia Ego is promoting the use of the following terms:

Straylight: The time of day before daybreak, before the sun rises.  The morning equivalent to the evening's twilight.

Mandelbrot baroque:  To focus endlessly on minutiae and ignore the big picture.  To attempt to explain the details of a concept at the cost of the central thesis.  Specifically a feature of an internet debate that becomes encumbered by quibbling about basic definitions and concepts and never approaches its central issue.

Preincarnation:  A person or concept that precedes a similar later figure or concept.  The inverse of a 'reincarnation'.

Reism: The degree to which an intellectual model or concept corresponds to the real-world process being modeled.  A model that describes the way a process actually occurs is reic.  For example, a given algorithm may be used to enable a computer to play chess.  If the algorithm actually describes the process that occurs in a human mind playing chess, that algorithm has a large degree of reism; it is reic.

Nom électronique: An online name or 'handle' meant to collect all digital material corresponding to a single person.  The electronic equivalent of a nom de plume or pen name.  Thus the sound a data miner makes is "nom nom nom", the same as Cookie Monster.

Nicholas Bourbaki: Following the pattern of a fictional French mathematician, an individual or collective name to be entered into a name field in order to preserve the user's anonymity.  A proposed standard nom electronique or pseudonym in instances where said name must appear to be an Euro-American given name.

Public school girls' disease (PSGD): The sad pathology of our culture wherein young women are trained to hide their intelligence, creativity, and critical thinking skills for the illusion that boys will like them that way.  While many cases can be cured by exposure to higher education, too many bright minds are lost each year.  We need to act now to stop the spread of this disease.

Iff:  Pronounced "if-eff", a verbal and notational shorthand for the phrase "if and only if".  The verbal form of the <=>, ≡, or ↔ operator.

Truvial: The truth value of a statement that is true, but for entirely unremarkable reasons or for reasons that have nothing to do with the central thesis of an argument.