1640s, "having no indication of time," from date (n.1) + -less. From 1923 as "free from engagements or appointments," from date (n.3).
the dateless rise and fall of the tides
dateless customs
a dateless letter
few characters are so dateless as Hamlet
dat
data
datable
date
dated
dateless
dateline
dating
dative
datum
daub
