The English name, Parson Bird, has fallen into disuse but came about because at first glance the Tūī appears completely black except for a small tuft of white feathers at its neck and a small white wing patch, causing it to resemble a parson in religious attire.

Tūī have faded browner patches on the back and flanks, a multicoloured iridescent sheen that varies with the angle from which the light strikes them, and a dusting of small, white-shafted feathers on the back and sides of the neck that produce a lacy collar.