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.
Source: wiktionary
Ranked by relevance and common usage.
Keep "unconvertible" when the sentence already sounds natural, when a synonym would add unintended emphasis, or when readers need the most familiar wording. A synonym should clarify or sharpen the message, not simply make the sentence look more varied.
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3 total sentences available.
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.
Source: wiktionary
If the situation created by the War has transformed also the English circulation into unconvertible paper money, this is merely a passing fact.
Source: wiktionary
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service on the Great Western Railway at the end of 1891, sixty-nine were unconvertible to the standard gauge, and were withdrawn from service when Brunel's 7 ft.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.
Source: wiktionary
Closest matches include inconvertible, unexchangeable.
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