rod

Definition

noun
  1. a stick shape with rounded ends
    Example Some bacteria are shaped like rods or are rod-shaped.
  2. one of two types of light-sensitive cell in the retina of the eye. Rods are sensitive to dim light, but not to colour.
    See also cone
COMMENT Rod cells in the eye are sensitive to poor light. They contain rhodopsin or visual purple, which produces the nervous impulse which the rod transmits to the optic nerve.
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