Adults are dark brown above and gray below.
Immatures have typical thrush mottled breast. Very little information is available on the species morphological description. Some authors suggested the Polynesian Turdus poliocephalus was the ancestor of Phaeornis, but Amadon reinvestigated the question and came to the same conclusion as Stejneger. Later they were considered subspecies or races of Phaeornis obscurus. The 1986 supplement to the AOU list gives Olomao as the official common name.