Sentence:  Such &#91;r-coloring&#93; may also be represented by adding a <WSD>diacritical hook</WSD> to a vowel letter [ᶒ, ɚ, ᶗ], or by making use of Kenyon's “hooked schwa” [˞]. 
Meaning of the word marked with <WSD> tags:  A (retroflex hook) ((̢)).