For ever and a day

What's the meaning of the phrase 'For ever and a day'?

Indefinitely.

What's the origin of the phrase 'For ever and a day'?

Of course, for ever and a day is an dramatic construct with no literal meaning - for ever is for ever, we can't add days to it. This form of dramatic emphasis has been used many times, a recent example being The Beatles' song 'Eight Days a Week'.

Shakespeare coined this and used it in The Taming of the Shrew, 1596:

BIONDELLO   I cannot tell; expect they are busied about a
      counterfeit assurance: take you assurance of her,
      'cum privilegio ad imprimendum solum:' to the
      church; take the priest, clerk, and some sufficient
      honest witnesses: If this be not that you look for,
      I have no more to say, But bid Bianca farewell for
      ever and a day.

He must have liked it as he used it again in As You Like It, 1600:

ROSALIND: Now tell me how long you would have her after you have possessed her.
ORLANDO: For ever and a day.

See other phrases and sayings from Shakespeare.