Definition of cortex in US English:



  • 1The outer layer of the cerebrum (the cerebral cortex), composed of folded gray matter and playing an important role in consciousness.

    • ‘Cats have frontal, temporal, occipital, and parietal lobes of their cerebral cortex, as we do, and these brain regions are composed of gray and white matter.’
    • ‘The frontal cortex is important in planning, impulse control, and attention.’
    • ‘Careful prospective and controlled studies of autonomic function will clarify the roles of the cortex and the brainstem in the generation and expression of seizures.’
    • ‘Parts of the thalamus, and the frontal lobes of the cerebral cortex that are important in controlling mood, also connect to the hypothalamus.’
    • ‘In fact, the cortex, midbrain, medulla and spinal cord are already simultaneously active when a baby moves a limb.’
    1. 1.1 An outer layer of another organ or body part such as a kidney (the renal cortex), the cerebellum, or a hair.
      • ‘The cortex (inner layer) of your hair is protected by the cuticle (outer layer).’
      • ‘This effect may be attributed to the decoupling of the actin cortex from the plasma membrane.’
      • ‘Such materials are known to be harder than noncomposites, such as the nonmelanic [beta] keratin that forms the cortex of white feathers.’
      • ‘The cortex and plasma membrane were modeled as thin elastic shells.’
      • ‘The nucleus accumbens is involved in motivation and reward, and the parietal cortex is important for sensory-motor function.’
      • ‘A similar result was obtained in an autopsy study in which the cadmium concentration of the kidney cortex was analyzed.’
      • ‘A split end occurs when the protective cuticle is worn away on the tip of a strand, allowing the fibers of the cortex to unravel and the hair to split lengthwise.’
      • ‘As well, the pigments used have less capacity for oxygenation and thus stay small enough to be removed from the hair cortex in 6 to 12 shampoos.’
      • ‘The polar bodies lie near the cortex and are not visible in this plane of focus.’
      • ‘The eye has been compared to a camera due to its ability to process images for interpretation by the occipital cortex of the brain.’
      • ‘Distribution of the cadmium concentration in the kidney cortex, liver, and lung, with respect to age, is shown in Figure 1.’
      • ‘So this is taking the information that's pouring into the sensory part of our brain, the back cortex, and getting them to translate it into activities at the front of our brain?’
      • ‘The cortex is the middle layer where pigment is located.’
      • ‘Once incorporated into the cortex of the hair, these traces of drug are permanently retained and substantially immune to any attempts to remove them.’
      • ‘The infection spreads and destroys the epiphyseal cortex, the intervertebral disc and the adjacent vertebrae.’
      • ‘The cortex of the bone becomes thinned leading to pathologic fracturing and distortion of the bones in the face and skull.’
      • ‘The amount of melanin in the cortex of each hair determines its color.’
      • ‘The medulla, supplied by vasa recta, receives less blood than the kidney cortex.’
      • ‘The color of a person's hair is determined by the amount and distribution of melanin in the cortex of each hair (the same melanin that's found in the epidermis).’
      • ‘The prefrontal cortex is also the organ of imagination.’
    2. 1.2Botany An outer layer of tissue immediately below the epidermis of a stem or root.
      • ‘The notion that the root cortex of flowering plants that grow in aquatic or wetland environments under hypoxic conditions is comprised primarily of enlarged air spaces, or lacunae, has been considered for at least 150 years.’
      • ‘The photographs indicate movement of oil from treated leaf surfaces to stems and extensive distribution of oil in the mesophyll, cortex, phloem, xylem, and pith of plant tissues.’
      • ‘It should be pointed out that by day 6 the leaf blade, the petiole and the stem cortex had lost a similar percentage of water.’
      • ‘The soil-borne mycorrhizal fungi colonize the root cortex biotrophycally, then develop an external mycelium which is a bridge connecting the root with the surrounding soil microhabitats.’
      • ‘Embedded in the cortex are numerous leaf traces that enter leaf petioles in the outer cortex and root mantle.’
      rind, skin, peel, sheath, covering, outer layer, coating, casing, crust
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Late Middle English: from Latin, literally ‘bark’.