Of or relating to a group of passerine birds including the thickheads or whistlers of Australasia.
These birds were formerly regarded as a subfamily Pachycephalinae in the family Laniidae, or later in the family Muscicapidae. They are now usually placed in a separate family Pachycephalidae, into which other related birds may be placed by some authors.
Late 19th century; earliest use found in The Century Dictionary. From scientific Latin Pachycephalinae, subfamily name from Pachycephala, genus name + -inae.