To insert an extra leap day into a calendar in order to maintain synchrony with natural phenomena. / To insert an extra month into a calendar for the same purpose. The Hebrew calendar has such a month.

Describing a time period inserted between others; leap, (as in leap day, leap month, or leap year)

Such a time period

(finance) The total number of contracts outstanding between market participants in a market for futures, options, or other derivatives.

An optical filter in which the wavelengths that are not transmitted are removed by interference rather than by absorption or scattering.

An instrument used to study the differences in the phase of light transmitted through a specimen.

(physics) A property, characteristic of the state of a thermodynamic system, the change of which is equal to the heat absorbed minus the work done by the system.

(physics) any of several instruments that use the interference of waves to determine wavelengths and wave velocities, determine refractive indices, measure small distances, temperature changes, stresses, and many other useful measurements.

(geometry) The inner angle between two sides of a polygon.

(visual arts) A decorative element found especially in early medieval art