|a screen or mat covered with a dark material for shielding a camera lens from excess light or glare.|
|a calculus or concretion found in the stomach or intestines of certain animals, esp. ruminants, formerly reputed to be an effective remedy for poison.|
perseveration per·sev·er·a·tion (pər-sěv'ə-rā'shən)
Uncontrollable repetition of a particular response, such as a word, phrase, or gesture, despite the absence or cessation of a stimulus, usually caused by brain injury or other organic disorder.
The tendency to continue or repeat an act or activity after the cessation of the original stimulus.