The part of a distillation apparatus that cools down vapour till it becomes a liquid. There are two main types of condensers. One is simply an inner tube that is cooled by an outer jacket filled with a liquid like water.
The other type has the inner tube filled with small (usually glass) beads or other shaped small bits of material. The distillate is taken from the top. This type of condenser in effect does thousands of tiny condensations (they occur on each bead) and produces a much more pure product. To achieve a similar effect with the other type, you need to do multiple distillations.