From The Collaborative International Dictionary of English v.0.48:
Inclusion \In*clu"sion\, n. [L. inclusio: cf. F. inclusion. See
Include.]
[1913 Webster]
1. The act of including, or the state of being included;
limitation; restriction; as, the lines of inclusion of his
policy. --Sir W. Temple.
[1913 Webster]
2. Something that is included.
[PJC]
3. (Min.) A foreign substance, either liquid or solid,
usually of minute size, inclosed in the mass of a mineral.
[1913 Webster]
4. (Biol., Cytology) A small body suspended within the
cytoplasm of a cell.
[PJC]
5. (Logic, Math.) The relationship existing between two sets
if one is a subset of the other.
[PJC]