Octagon

An octagon is a square that had its four corners sanded off, and now has eight of them.
Bookshelf

A bookshelf stores books in order of how clever they make you look, not the order you read them.
List of things that are cold

A list of cold things, chosen by touch: anything that made the tester say ‘ooh’ got in.
Drizzle

Drizzle is rain that hasn’t committed, and is called ‘not really raining’ by 94% of the people it soaks.
Teal

Teal is blue to anyone who thinks it is green, and green to anyone who has just said it is blue.
Mud

Mud is either wet earth or dirty water, a question that has divided scholars and ruined trousers.
Stalagmite

A stalagmite grows upward about a centimetre a century, and has no plans for when it gets there.
White

White contains every colour at once, which is why it is the only colour that has never been asked to choose.
Bucket

A bucket surrounds its contents on every side but the top, which it leaves open as a courtesy.
Shadow

A shadow is made of light that isn’t there, which makes it very hard to steal, though one try got close.