ENGLISH
REFERENCE

shale

n. · v.
US //ˈʃeɪɫ// UK //ʃˈeɪl// shale
  1. 1 sedimentary rock (n.)
    C1 Advanced Technical Science

    a soft, dark rock that was formed from mud and can be split into thin, flat pieces.

    a fine-grained sedimentary rock formed by the compaction of silt and clay-size mineral particles; it is typically fissile, meaning it splits easily along laminations.

    Example

    The geologist found fossils of ancient leaves pressed between the layers of shale.

    Example

    The extraction of natural gas from deep shale formations has significantly altered the global energy landscape over the last decade.

    Usage

    Often used as an uncountable noun when referring to the material, but countable when referring to specific geological formations.
    • mudstone
    • claystone
  2. 2 a shell or husk (n.)
    C2 Proficiency Archaic Dialect

    the outer shell or covering of a seed or fruit.

    the outer covering, husk, or pod of a plant or seed.

    Example

    He removed the dry shale from the grain before grinding it.

    Example

    In certain regional dialects, the term shale is still applied to the protective husks of legumes during the harvest season.

    Teacher's tip

    This sense is extremely rare in modern English; learners will almost exclusively encounter the geological meaning.
  3. 3 to remove a shell (v.)
    C2 Proficiency Archaic

    to take the outer skin or shell off something.

    to remove the shell, husk, or outer coating from a seed or fruit.

    Example

    The workers spent the afternoon shaling the peas for the evening meal.

    Example

    The traditional process involved shaling the nuts by hand before they were laid out to dry in the sun.

    Usage

    A transitive verb taking a direct object.
Origin

From Middle English schale (“shell, husk; scale”), from Old English sċealu (“shell, husk, pod”), from Proto-West Germanic skalu, from Proto-Germanic skalō, from Proto-Indo-European (s)kelH- (“to split, cut”), from (s)kel- (“to split, cleave”). See also West Frisian skaal (“dish”), Dutch schaal (“shell”), schalie (“shale”), German Schale (“husk, pod”); also Lithuanian skalà (“splinter”), Old Church Slavonic скала (skala, “rock, stone”), Polish skała (“rock”), Albanian halë (“fish bone, splinter”), Sanskrit कल (kalá, “small part”); also Hittite [script needed] (iškalla, “to tear apart, slit open”), Lithuanian skélti (“to split”), Ancient Greek σκάλλω (skállō, “to hoe, harrow”). Doublet of scale. See also shell.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

Related words

Last updated June 20, 2026