Ritual
If "magic" is the impression of perception onto reality, then "ritual" is "a concerted effort spent on changing perception." Ritual differs from general _spellcasting_ in that spells are free-form, and typically single-person. Rituals have a bit more structure to them, and they imply group activity. This isn't to say that they require stodgy attire or calling the corners. A shared in-joke is a ritual, one of the most powerful because it affirms the connections between people.
