| toxic amblyopia | Blindness due to optic neuritis caused by methyl alcohol, lead, arsenic, quinine, or other poisons. (05 Mar 2000) |
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| extinction | 1. <ecology> The death of an entire species. 2. <psychology> The procedure of presenting the conditioned stimulus without reinforcement to an organism previously conditioned. It refers also to the diminution of a conditioned response resulting from this procedure. (27 Jun 1999) |
| extinction angle | <microscopy> The angle between the nearer vibration direction and a prominent direction of the crystal. It never exceeds 45 degrees (05 Aug 1998) |
| extinction coefficient | <chemistry> A constant used in the Beer-Lambert Law which relates the concentration of the substance being measured (in moles) to the absorbance of the substance in solution (how well the substance in solution blocks light beamed through it from getting out on the other side). (09 Oct 1997) |
| extinction factor | <microscopy> In a polarizing or Differential Interference Contrast microscope, the ratio of the amount of light that is transmitted with the axes of the polars parallel over the amount transmitted with their axes crossed. Unless the lenses are rectified, the extinction factor drops exponentially as the numerical aperture is increased. Acronym: EF (26 Mar 1998) |
| extinction oblique | <microscopy> Vibration directions oblique to the long direction of the crystal or fibre. (05 Aug 1998) |
| extinction parallel | <microscopy> Vibration directions parallel and perpendicular to the long direction of the crystal or fibre. (05 Aug 1998) |
| extinction symmetrical | <microscopy> Vibration directions bisecting a prominent crystal profile angle. (05 Aug 1998) |
| undulose extinction | <microscopy> Nonuniform extinction of a substance between crossed polars. The areas of complete extinction move progressively with a fanlike motion across the surface of the substance as the stage is rotated. (05 Aug 1998) |