A cloning vector is a small piece of DNA that can be stably maintained in an organism, and into which a foreign DNA fragment can be inserted for cloning.
Plasmids (like pBR322) is a very common cloning vector.
YAC (Yeast Artificial Chromosome) and BAC (Bacterial Artificial Chromosome) are used as vectors in human genome project.
Probe a radiolabelled piece of DNA which is used in autoradiography.