The Romans did not have a symbol for nothing (zero), and were so hampered by the lack that they were incapable of contributing to mathematical knowledge.

– A.C. Grayling, The Reason Of Things

What else do we still not have a symbol for, or a word for? Future generations may look back on us and wonder, how did nobody not realise that was missing?

If there is no means to express something, does it really exist?