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thickness

n.
US //ˈθɪknəs// UK //θˈɪknəs// thick·ness
  1. 1 measurement of depth (n.)
    B1 Intermediate

    the distance between the front and back or top and bottom surfaces of something.

    the dimension of an object measured through its smallest side, perpendicular to its length and width.

    Example

    The thickness of the walls helps keep the house warm in winter.

    Example

    The engineer calculated the required thickness of the steel plating to ensure it could withstand the pressure of the deep-sea environment.
    • thinness
  2. 2 liquid consistency (n.)
    B2 Upper Intermediate Cooking

    how heavy, solid, or sticky a liquid is.

    the degree of viscosity or density in a fluid or semi-solid substance.

    Example

    Cook the sauce for ten minutes until it reaches the right thickness.

    Example

    The chef adjusted the thickness of the gravy by adding a small amount of cornstarch mixed with cold water.
    • runniness
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  1. 3 a layer (n.)
    B2 Upper Intermediate

    a single layer of a material.

    a single layer or stratum of a substance, often used when multiple layers are applied.

    Example

    Use a double thickness of paper so the ink doesn't bleed through.

    Example

    The winter coat featured a triple thickness of insulation, making it suitable for Arctic expeditions.
  2. 4 lack of intelligence (n.)
    C2 Proficiency Informal British English

    the quality of being slow to understand things.

    the state of being intellectually slow or dull-witted.

    Example

    I couldn't believe his thickness when he failed to see the obvious joke.

    Example

    The manager was often frustrated by the sheer thickness of the new recruits who struggled with basic safety protocols.

    Teacher's tip

    This sense is primarily British and can be quite insulting; use 'slow' or 'unintelligent' in professional contexts.
Origin

From Middle English thikkenesse, thiknesse, from Old English þicnes (“thickness, viscosity, density, hardness; obscurity, cloud, darkness; thicket; depth, a thick body, anything thick or heavy”), from Proto-West Germanic *þikkwīnassī (“thickness”), equivalent to thick + -ness. Cognate with West Frisian tsjokkens (“thickness”), Old High German dickinessī, dikkinissi, diknissi (“thickness, density”). Eclipsed non-native Middle English crassitude (“thickness”) from Latin crassitūdō (“thickness”).

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