undated

Not marked with or showing a date.

Being such as to have long-lasting appeal without ever going out of style.

Not dated; having no date: as, an undated letter or bill.

Having a waved surface; rising and falling in waves toward the margin, as a leaf; waved. Also undate.

In heraldry, same as undé.

In botany, same as undulate.

Not dated; having no date; of unknown age.

Rising and falling in waves toward the margin, as a leaf; waved.

not marked with a date

of a style that will not go out of fashion; a classic