| 1. | without ever ending; eternally: to last forever. |
| 2. | continually; incessantly; always: He's forever complaining. |
| 3. | an endless or seemingly endless period of time: It took them forever to make up their minds. |
| 4. | forever and a day, eternally; always: They pledged to love each other forever and a day. |

forever and a day
For a very long time, as in He's been working on that book forever and a day. This hyperbolic expression probably originated as a corruption of the now obsolete for ever and ay. Shakespeare used it in The Taming of the Shrew (4:4): "Farewell for ever and a day." Today it is mainly a substitute for "very long time." [c. 1600]
Incessantly, ceaselessly, as in Will this racket never end? It's been going on forever and a day. [Colloquial; first half of 1900s]