(finance) An options strategy or position involving the simultaneous purchase and sale of options of the same class and strike price but with different expiration dates.

The period of duration from the first date of one month to the last date of the same month, which can thus vary from 28 to 31 days in length.

A calendar based on the movement of the Earth and the Moon around the Sun, which defines the year.

(law) A timespan of exactly 24 hours, measured from one midnight to the next. / A day having a conventional designation on a recognized calendar, such as a numerical identification within a named month.

A model of the chronology of the universe, scaling the scientifically accepted age of 13.8 billion years down to a single year, with the Big Bang taken as January 1 and the present moment taken as December 31.

plural of lunar calendar

plural of lunisolar calendar

(historical) A kind of astronomical diagram used to tell time in Ancient Egypt.

plural of diagonal calendar

A clock that also displays the date