One who delays, procrastinates, and puts off till tomorrow what can be done today, especially because of laziness or careless inattention. One who engages in cunctation, that is tardiness, foot-dragging, or procrastination.
The origin of cunctator is Latin, though it did not always have the derogatory connotation that it does now. One of the Roman generals (and onetime dictator) Fabius (Quintus Fabius Maximus Verrucosus, to be exact) was an opponent of Hannibal, and his tactics were to harass his enemy mercilessly by keeping his troops near Hannibal's but never attacking or joining in battle. Hence this Fabius was known as the Cunctator, or Fabius Maximus Cunctator.
Fabian is another locution derived from this Fabius, and the good Gritchka informs me that the Fabian Society was so named because of their wish to acheive socialism slowly, rather than through a speedy revolution.