inclusion
Pluralinclusions (some meanings)
- 1The act of taking something in by adding it to a group, set, or total.
The committee debated the inclusion of additional categories in the final report.
His inclusion on the guest list surprised several longtime regulars.
Similaraddition, incorporation
- 2An item added or attached to a group, set, or total.
The bonus track was a surprising inclusion on the reissued album.
Editors reviewed each proposed inclusion before finalizing the anthology.
Similaraddition
Note
Counted things take this sense: a new inclusion, a surprising inclusion, each proposed inclusion. It names the item itself, so it can take an article and a plural. The act of including is uncountable and usually travels with of, as in the inclusion of the poem. To choose between them, ask whether you mean the thing that was added or the adding of it.
- 3A foreign particle or substance enclosed within a material.
An inclusion in the steel caused the beam to crack under load.
Metallurgists examined the casting for inclusions before approving it.
Similarimpurity
Note
Here the Latin root shows through. Inclusio comes from includo, "to shut in, enclose," which is built on claudo, "to shut." English enclosure is a doublet from the same source. A foreign body sealed inside steel or glass is included in that older, literal way: it is enclosed rather than added. That is why the word so easily suggests a flaw hidden inside a material.
- 4Material trapped inside a mineral as it formed, often visible as a flaw in a precious stone.
The jeweler spotted an inclusion near the center of the emerald.
Gemologists use inclusions to tell natural stones from synthetic ones.
Note
Gemology's version of the foreign body in a material, and the one with a price attached. Cindy Lasiter's Diamonds in the Rough (2009) states the trade rule plainly: the fewer inclusions a diamond has, the better its clarity and value. She adds that inclusions can often be cut out while the stone is still in the rough. In this talk the word usually appears in the plural.
- 5A clump of stainable material gathered in a cell's nucleus or cytoplasm.
The cytologist identified an inclusion within the cell nucleus.
A viral inclusion in the cytoplasm confirmed the infection.
Note
A cell biologist's term, defined by what a dye reveals: material that gathers in the nucleus or cytoplasm and takes up stain. The location is often named alongside it, as in a nuclear inclusion or a cytoplasmic inclusion. Do not confuse it with the tissue sense, which works at a larger scale. That sense names an object lodged in tissue, not a stained clump inside a single cell.
- 6An object lying completely within a tissue, such as a cyst trapped beneath the skin.
The biopsy revealed an inclusion lodged deep within the dermis.
Doctors traced the lump to an inclusion buried in the soft tissue.
Note
Histology uses the word mostly inside a fixed phrase: the epidermal inclusion cyst, a cyst lying within the epidermis. In that phrase inclusion describes how the object sits, wholly enclosed by the surrounding tissue, rather than what it is made of. That fixed phrase is where most readers will meet this sense.
- 7A mapping in which the domain is a subset of the larger set it maps into, sending each element to itself.
The inclusion maps each element of the subset to itself in the larger set.
An inclusion from the integers into the rationals preserves every element unchanged.
Note
Mathematics keeps the most literal picture: a subset sitting inside a larger set, with each element sent to itself. Formally, it is a map ι: A → B where A ⊆ B and ι(a) = a, and it is often drawn with a hooked arrow. It changes nothing; its job is to record that A lives inside B. A standard phrasing is "the inclusion of the integers into the rationals."
Less common meaning
- 8A restriction or limitation imposed upon something.
The charter bound the guild with an inclusion that none could escape.
He chafed under the inclusion the elders had placed on his speech.
Note
This meaning has long fallen out of use. It comes straight from the Latin sense of shutting in, told under the foreign body in a material: to enclose something is also to confine it. Readers will meet it only in older texts, where an inclusion is a limit placed on someone rather than something added. In modern writing it would be misread, so use restriction or limitation instead.
Practice
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Origin
This word was borrowed from Latin inclusio, from the verb inclūdō ("to shut in, enclose, insert"), which combines in- ("in") with claudō ("to shut"), ultimately going back to Proto-Indo-European *kleh₂u- ("key, hook, nail"). It is a doublet of enclosure.