locus

noun

• A place or locality, especially a centre of activity or the scene of a crime.

  "The cafeteria was the locus of activity."

• The set of all points whose coordinates satisfy a given equation or condition.

  "A circle is the locus of points from which the distance to the center is a given value, the radius."

• A fixed position on a chromosome that may be occupied by one or more genes.
• (chiefly in the plural) A passage in writing, especially in a collection of ancient sacred writings arranged according to a theme.