Pronunciation: [pˈɪləs] (IPA) 
The word "pilus" is often misspelled as "pilous" due to the silent "u" in the pronunciation. The correct spelling is pronounced as [ˈpaɪ.ləs], with emphasis on the first syllable "pi" and the final syllable "lus" rhyming with "fuss." In microbiology, a pilus is a hair-like structure that is used for bacterial conjugation or attachment to surfaces. Proper spelling is important in science to avoid confusion and accurately convey information.
The term "pilus" denotes a small, slender, hair-like structure that is present on the surface of certain living organisms, including bacteria and some eukaryotic cells. These structures are primarily involved in bacterial conjugation, which is a form of genetic transfer between bacterial cells.
In the bacteriological context, a pilus is a thin, elongated tubular appendage that extends from the cell surface and is involved in cell adhesion, motility, and the exchange of genetic material during conjugation. Bacterial pili are composed of protein subunits called pilins and can vary in length, number, and composition, depending on the bacterial species. These structures play a crucial role in mediating bacterial attachment to host cells, assisting in the colonization process, and enhancing bacterial pathogenicity.
Pili in eukaryotic cells are primarily related to cellular motility and sensory functions. For instance, in the cells of the inner ear, hair-like structures called stereocilia form bundles that convert sound waves into electrical signals, allowing for the perception of auditory stimuli.
Overall, pili serve a diverse range of functions across various organisms, but they generally share the common characteristic of being elongated, hair-like appendages that contribute to cell-cell interactions, motility, or sensory perception.
Gen. and nom. pl. Pili, gen. pl. Pilorum. Hair, one of the fine, thread-like appendages of the skin, covering more or less thickly the entire body, except the palms and soles and the flexor surfaces of the joints. A hair consists of radix or root, embedded in the hair follicle, and a free portion, scapus, stem or shaft.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.
The word pilus has Latin origins. It comes from the Latin noun pilus, which means hair or body hair. This Latin term is also the basis for other related words in various languages, such as pile in English and pelo in Spanish, both of which mean hair.
