insolvable

It is one of the most insolvable questions in history why so little effort was made by the French to save the Maid's life.

The problem seemed insolvable; but Trueman Harwell had not played the part of a machine so long without result.

This apparently insolvable problem was solved by Watt in the most simple manner.

The sheriff of neither county could afford to bother his head long over an insolvable mystery.

Heredity thus becomes a convenient name by which to denominate the insolvable.