inclusion

noun

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”). By surface analysis, include + -sion. Doublet of enclosure.

1. An addition or annex to a group, set, or total.

   “The poem was a new inclusion in the textbook.”

2. 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. Anything foreign that is included in a material.
4. 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.”

5. A nuclear or cytoplasmic aggregate of stainable substances.
6. An object completely inside a tissue, such as epidermal inclusion cyst, a cyst in the epidermis.
7. A mapping where the domain is a subset of the image.
8. Restriction; limitation.