locus
- 1A particular place or locality, especially one that is the center of some activity or the scene of a crime.
The old market square remains the locus of the town's social life.
For a few years, the tiny café on Main Street was the locus of the town's music scene.
UsageMostly the locus of something: the locus of town life. Plural loci or locuses.
- 2In genetics, the specific place on a chromosome, or other stretch of DNA or RNA, where a particular gene or sequence is found.
The team traced the inherited disorder to a single locus on the short arm of the chromosome.
The study compared hundreds of loci across the two populations.
Note
Geneticists use the word for an address, not for the gene that lives there. The alternative versions of a gene, its alleles, sit at the same locus on matching chromosomes, which is why one can ask what an organism carries at a given locus. It works at several scales: a locus lies within a band or region of a chromosome and can itself be divided into subloci.
Checked 30 Oct 2026 · 5 facts
- A genetic locus identifies a location rather than the gene occupying it. genome.gov
- Alleles are alternative versions of a gene occupying the same locus on homologous chromosomes. genomicseducation.hee.nhs.uk
- An organism's alleles can be identified at a particular locus. genomicseducation.hee.nhs.uk
- A locus can be located within a chromosome band or region. ncbi.nlm.nih.gov
- A locus can contain smaller subdivisions called subloci. frontiersin.org
- 3In geometry, the curve, surface, or other figure made up of every point that meets a given condition or equation.
The locus of points equidistant from two fixed points is a straight line.
Parabolas, ellipses, and hyperbolas can each be described as loci defined by a focus and a directrix.
Note
Geometry uses the word for all the points meeting a condition, which can sometimes be a single point. More often it is a line or curve: a circle is the locus of points at a fixed distance from its center. Locus problems run the other way, giving only the condition and asking what figure the points form.
Checked 3 Nov 2026 · 4 facts
- A locus comprises all points satisfying a given condition. academic.sun.ac.za
- A locus can consist of a single point. andrew.cmu.edu
- A circle consists of the points at a fixed distance from its center. en.wikipedia.org
- Locus problems ask for the geometric figure determined by a condition or equation. academic.sun.ac.za
- 4The seat or source of something abstract, such as power, control, responsibility, or causation: where it resides or where it begins.
The reforms shifted the locus of decision-making from Washington to the state capitals.
The town had two rival loci of authority, the church and the mill owner.
UsageUsually followed by of: the locus of power, an internal locus of control. Plural loci.
Similarcenter, seat, focus, source
Note
Here the word for a physical place moves into abstraction, and it nearly always takes of: the locus of power, of decision-making, of responsibility.
Less common meaning
- 5A passage in a piece of writing, especially one in a collection of ancient sacred texts arranged by theme.
Practice
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Origin
Borrowed from Latin locus.
Checked 1 Nov 2026 · 1 fact
- English locus was borrowed from Latin locus. en.wiktionary.org