| BIR | the characteristic sound produced by a bird |
|---|---|
| BIR | watch and study birds in their natural habitat |
| BIR | splitting a ray into two parallel rays polarized perpendicularly |
| BIR | relating to or characterized by double refraction |
| BIR | a stiff cap with ridges across the crown |
| BIR | consisting of or made of wood of the birch tree |
| BIR | cause to spin |
| BIR | cause a floating log to rotate by treading |
| BIR | cause a floating log to rotate by treading |
| BIR | rotating a log rapidly in the water (as a competitive sport) |
| BIR | a city in central England |
| BIR | the largest city in Alabama |