Dateless

wiktionary

ref

Unknown. Perhaps derived from Old English þeatless(“thoughtless, without plan”). See also deedless.

Coined between 1585 and 1595 from date +‎ -less [1] [2]

etymonline

ref

dateless (adj.)

1640s, "having no indication of time," from date (n.1) + -less. From 1923 as "free from engagements or appointments," from date (n.3).