month of Sundays

Etymology
Probably a reference to the passing of as many Sundays as there are days in a month, that is, between 28 and 31 weeks.

Noun

 * 1)  A very long time; a period regarded as too long.

Usage notes
The term is often used negatively, for example, “never in a month of Sundays” or “not in a month of Sundays”.

Translations

 * Finnish: ikiaikoihin,
 * Serbo-Croatian: dugo kao gladna godina
 * Spanish: más largo que un día sin pan, más largo que el parto de la burra