Definition
Plain language
One tiny speck that makes a whole liquid suddenly crystallize around it.
As stated in the literature
A threshold-triggered phase change seeded by a single site, contrasted with gradual dilution; used to describe why one contaminated retrieval result produces nearly the same collapse as full contamination.
Why it matters: It explains why contamination isn't proportional — one bad item among many can tip a whole system rather than just diluting into the average.
For example, dropping a single grain of sugar into a supersaturated glass makes crystals shoot through the entire liquid within seconds.