A thaumatrope is an optical toy that was popular in the 19th century. A disk with a picture on each side is attached to two pieces of string. When the strings are twirled quickly between the fingers the two pictures appear to blend into one due to the persistence of vision.

What does the word thaumatrope mean?

: an optical instrument or toy that shows the persistence of an impression upon the eye and that consists of a card having on its opposite faces different designs that appear to the eye combined in a single picture when the card is whirled rapidly round a diameter by the strings that hold it.

Where did the word thaumatrope come from?

Thaumatropes are often seen as important antecedents of motion pictures and in particular of animation. The name translates roughly as "wonder turner", from Ancient Greek: θαῦμα "wonder" and τρόπος "turn".