The quality or state of being ambiguous; the characteristic of being unclear or having multiple possible meanings.
From ambiguous + -ness, a standard English nominalization. Both ambiguousness and ambiguity exist, with ambiguity being older and more common.
English has multiple ways to make nouns from ambiguous—we can say ambiguity, ambiguousness, or even ambiguousness—showing that English loves redundancy and lets speakers choose the version that fits their style.
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