Singular point

From Glossary of Meteorology

singular point

  1. Of a differential equation, a point at which the coefficients are not expandable in a Taylor series.

  2. Of a function of a complex variable, a point at which the function does not have a derivative.

  3. (Also called singularity.) Of a flow field, a point at which the direction of flow is not uniquely determined, hence, a point of zero speed, for example, a col.