From BiblePortal Wikipedia

Webster's Dictionary [1]

(n.) The forty days of fast preceding Easter; Lent.

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [2]

(fortieth day) is a name sometimes applied to the Lenten season, or more properly to the first Sunday of Lent (q.v.). It is so called by analogy with the three Sundays which precede Lent, and which are called respectively Septuagesima, seventieth; Sexagesima, sixtieth; and Quinquagesima, fiftieth. The whole period of Quadragesima is in the Roman Catholic Church accounted as tempus clausum.

The Nuttall Encyclopedia [3]

E . fortieth), a name given to Lent because it lasts forty days, and assigned also to the first Sunday in Lent, the three Sundays which precede it being called respectively Septuagesima, Sexagesima, and Quinquagesima.