1. vertigo in sheep caused by a tapeworm larva encysted in the brain.
Word OriginMiddle English (in the senses ‘reckless, violent’ and ‘intractable, obstinate’): shortening of Old French esturdi ‘stunned, dazed’. The derivation remains obscure; thought by some to be based on Latin turdus ‘a thrush’ (compare with the French phrase soûl comme une grive ‘drunk as a thrush’).