"When Washoe, a chimp who learned American Sign Language, saw a swan and did not know the sign for it, she combined two signs that she did know to give it the name "waterbird." This feat showed that she had a linguistic ability called

productivity linguistic ability

Explanation:

Productivity linguistic ability -

It refers to the ability or the creativeness to create new words by using the basic words of a particular language , is referred to as productivity .

Productivity is also known as creativity or open - endedness .

It is one of the most common and simplest method to generate new words of phrases .

Hence , from the given scenario of the question ,

Washoe indicates the swan as a waterbird , is the indication of productivity .