What does annual mean?
The definition of annual
An”nu*al, a.
Etym: [OE. annuel, F. annuel, fr. L. annualis, fr. annus year. Cf. Annals.]

1 Of or pertaining to a year; returning every year; coming or happening once in the year; yearly. The annual overflowing of the river [Nile]. Ray.
2 Performed or accomplished in a year; reckoned by the year; as, the annual motion of the earth. A thousand pound a year, annual support. Shak.
2 Lasting or continuing only one year or one growing season; requiring to be renewed every year; as, an annual plant; annual tickets. Bacon.

An”nu*al, n.
1 A thing happening or returning yearly; esp. a literary work published once a year.
2 Anything, especially a plant, that lasts but one year or season; an annual plant. Oaths . . . in some sense almost annuals; . . . and I myself can remember about forty different sets. Swift.
3 (R. C. Ch.)
A Mass for a deceased person or for some special object, said daily for a year or on the anniversary day.