plural of question period

plural of sidereal period

(physics) Half of the period of a wave etc; typically the time taken for part of a wave to be replaced by a similar part that is out of phase.

(of an astronomic object) The time taken to rotate about its axis relative to the background stars.

rotational period

Time period between the receipt of the letter of dismissal and the last working day.

plural of gestation period

plural of honeymoon period

plural of menstruation period

plural of refractory period