inclusion

Etymology

Borrowed from Latin inclusio, inclusionis, from the verb Latin inclūdō (“to shut in, enclose, insert”), from in- (“in”) + claudō (“to shut”), ultimately from Proto-Indo-European *kleh₂u- (“key, hook, nail”). Doublet of enclosure.

noun

1. (countable) An addition or annex to a group, set, or total.
   The poem was a new inclusion in the textbook.
2. (uncountable) The act of including, i.e. adding or annexing, (something) to a group, set, or total.
   The inclusion of the poem added value to the course.
3. (countable) Anything foreign that is included in a material,
4. (countable, mineralogy) Any material that is trapped inside a mineral during its formation, as a defect in a precious stone.
   The fewer inclusions a diamond has, the better is its clarity and value. Often the inclusions can be cut out of a diamond in the rough. 2009, Cindy Lasiter, Diamonds in the Rough, Xulon Press, page xi
5. (cytology) A nuclear or cytoplasmic aggregate of stainable substances.
6. (histology) An object completely inside a tissue, such as epidermal inclusion cyst, a cyst in the epidermis.
7. (mathematics) A mapping where the domain is a subset of the image.
8. (obsolete) Restriction; limitation.