unconvertible

comparative more unconvertible · superlative most unconvertible

1. That cannot be converted.

   If the situation created by the War has transformed also the English circulation into unconvertible paper money, this is merely a passing fact.

   1922, Francesco Saverio Nitti, Peaceless Europe

   2 more examples

   I can only recommend you to read again Darwin's account of the horse family and its comparison with pigeons; and if that does not convince and stagger you, then you are unconvertible.

   1916, James Marchant, Alfred Russel Wallace= Letters and Reminiscences, Vol. 1 (of 2)

   Of the 196 broad-gauge locomotives in service on the Great Western Railway at the end of 1891, sixty-nine were unconvertible to the standard gauge, and were withdrawn from service when Brunel's 7 ft. gauge was finally abolished nearly five months later.

   1955 August, “The Why and the Wherefore: Last Broad-Gauge Engines at Work”, in Railway Magazine, page 586