the main character in the stories by Sir Arthur Conan Doyle. He is a very clever detective (=someone whose job is to solve crimes and catch criminals) and he always notices very small details and then uses them to guess what has happened.
Definition from the Longman Dictionary of Contemporary English Advanced Learner's Dictionary.
Dictionary pictures of the day
Do you know what each of these is called?
Click on any of the pictures above to find out what it is called.