Impaction

Noun

1. Compression; the packing together of loose matter.
2. something packed together tightly; a mass of densely-packed matter
3. A solid, immobile bulk of stool.
4. Failure of a tooth to erupt into the dental arch, because of adjacent teeth, dense overlying bone, excessive soft tissue, or other factor.
5. The situation where an educational institute, usually a college or university, receives more applications from qualified applicants than the number of spaces available, meaning that meeting the minimum admission requirements does not guarantee acceptance.