acrobat [E19th] The earliest acrobats were tightrope walkers, which explains why the word derives from Greek akrobatos, meaning ‘walking on tiptoe’. The akro- part of akrobatos meant ‘tip, end, or summit’ and is found in several other English words. The acropolis [L16th] of a Greek city, most famously Athens, was the fortified part, which was usually built on a hill. Acrophobia [L19th] is fear of heights. An acrostic [L16th] is a poem or puzzle in which the first letters in each line form a word or words.