Everything, every part, as in He packed up all his gear, the whole kit and caboodle, and walked out. This expression is a redundancy, for kit has meant "a collection or group" since the mid-1700s (though this meaning survives only in the full idiom today), and caboodle has been used with the same meaning since the 1840s. In fact caboodle is thought to be a corruption of the phrase kit and boodle, another redundant phrase, since boodle also meant "a collection."