adjective - working secretly, especially as a police officer trying to get information without people knowing who you really are
noun - the place where a crime happened and where the police look for clues and evidence
noun - a male reproductive cell that can join with a female egg to create a new life
noun - an animal or human in the early stages of development before birth, especially before all the main body parts are formed
noun - an organ that develops in the uterus during pregnancy to provide oxygen and nutrients to the developing baby and remove waste products from the baby's blood
adjective - not allowed or not suitable to do something or receive something, especially by law or by rules
adjective - feeling quietly sad or thoughtful, often for no clear reason
adjective - having a speckled appearance of light and dark colours mixed together
adjective - having a mixture of dark and white or grey hairs
noun - an unpleasant, harsh, or metallic ringing sound made by metal objects hitting each other
verb - to make a harsh, discordant, metallic sound, or to cause something to make such a sound
adjective - describing petrol that contains lead compounds