Cannibalism in a dream: what does it mean?
One of the strongest taboos there is, and in dreams it is nearly always about consumption in a figurative sense: something taking everything.
How do the four traditions read it?
Each reading below comes from a named tradition and a cited source, so you can see where it came from and decide what fits your dream. The four often disagree, and that is the point: a symbol rarely means one fixed thing, and the distance between Freud, Jung, modern research and myth tells you more than any single verdict could.
Freud
Freud discussed incorporation as an early way of taking something in, and would treat the taboo as the material rather than the act: a dream that breaks the strongest rule has chosen the strongest rule.
After Freud, The Interpretation of Dreams (Brill trans., 1913), public domain.Jung
For Jung the devouring can image something in a life consuming the dreamer entirely, and the horror reported usually attaches to the totality rather than to the flesh.
Our summary of a Jungian reading, in our own words, not Jung's. See Jung, ed., Man and His Symbols (1964).Modern
Under the continuity view this arrives through story and film rather than experience. Threat-simulation would treat being eaten as an evolutionarily old threat and among the oldest classes the theory covers.
Our summary of the continuity hypothesis, named by Calvin Hall and Vernon Nordby, The Individual and His Dreams (1972). Its correct scope is disputed; see Domhoff (2017) and the replies to him. Our summary of threat-simulation theory. See Revonsuo, Behavioral and Brain Sciences 23(6), 2000, 877-901. The theory is contested.Mythological
The accusation of cannibalism has been levelled at outsiders by almost every society at some point and is very rarely substantiated, which makes its history a study in how groups describe those they fear.
Rosmerta Publishing editorial synthesis (after Frazer; Bulfinch).How can writers use this symbol?
The same symbol, read as craft material rather than as a dream. What it does on the page, how genres use it differently, and what happens when you turn it inside out. Written for novelists, screenwriters and poets who need the symbol to actually work, and it ends with something to try.
In literature
Fiction uses cannibalism for taboo shock and occasionally for something better: survival writing treats it as an arithmetic problem, which is far more disturbing.
Rosmerta Publishing editorial synthesis. Our own words; no quoted text.What it does in a story
It marks a boundary crossed that cannot be uncrossed, which makes it a point of no return. Structurally it is nearly always an ending.
Genre conventions
Horror uses the reveal. Survival fiction uses the decision, which is the only version with moral weight. Satire uses it for consumption in the economic sense, which is a very old joke.
How to subvert it
Write the decision not to, and the consequences of that, over a long time.
Try this
Write a lifeboat conversation in which the subject is never mentioned and everyone is thinking about it.
Only the first of these names a source. What a symbol does in a story, how genres treat it, how to invert it and what to try are our editorial judgement as writers and editors, not findings from a body of research. They are offered as craft opinion and should be argued with.