Capricious connects unpredictable humans to hedgehog quills or leaping goats — and it became a legal standard for striking down arbitrary government decisions.
Given to sudden, unpredictable changes of mood or behavior. Subject to whim rather than reason or consistency.
From French capricieux, from Italian capriccioso, from capriccio (whim, sudden impulse). See caprice for the full etymological chain: possibly from capo (head) + riccio (hedgehog) Key roots: capriccio (Italian: "sudden whim, shiver"), capo + riccio (Italian: "head + hedgehog").
In music, capriccioso is a performance direction meaning "freely, in a whimsical or capricious manner" — the player should deviate from strict tempo and interpretation to sound spontaneous and unpredictable. Tchaikovsky's Capriccio Italien (1880) captures this spirit. The word capricious is often used in legal contexts to describe arbitrary decisions: courts will overturn government actions that are "arbitrary and capricious," a legal standard from U.S. administrative