| 1. | division into two parts, kinds, etc.; subdivision into halves or pairs. |
| 2. | division into two mutually exclusive, opposed, or contradictory groups: a dichotomy between thought and action. |
| 3. | Botany. a mode of branching by constant forking, as in some stems, in veins of leaves, etc. |
| 4. | Astronomy. the phase of the moon or of an inferior planet when half of its disk is visible. |