1. 无期限的：dated 有日期的 | dateless 无期限的 | dateline 日期变更线

2. 无日期的：无任所大使ambassador-at-large | 无日期的dateless | 无融合生殖apomixis

3. 无日期的/无限期的：dated /过时/ | dateless /无日期的/无限期的/ | dateline /日期变更线/日界线/日期栏/

adj

1. unaffected by time

    e.g. few characters are so dateless as Hamlet
           Helen's timeless beauty

    Synonym: timeless

2. not bearing a date

    e.g. a dateless letter

    Synonym: undated

3. of such great duration as to preclude the possibility of being assigned a date

    e.g. dateless customs

4. having no known beginning and presumably no end

    e.g. the dateless rise and fall of the tides
           time is endless
           sempiternal truth

    Synonym: endlesssempiternal