A Locus

1. A place or locality, especially a centre of activity or the scene of a crime.
2. (mathematics) The set of all points whose coordinates satisfy a given equation or condition.

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

Sometimes confused with locust.