Chinless means having a weak jaw, and thought feeble because of it. A chinless face, chinless and vague, a chinless wonder.
The judgement is nonsense but the phrase is fixed: a chinless wonder is a British insult for a rich, useless and badly bred young man, and it belongs to a class joke about aristocratic inbreeding rather than to any real physiognomy.
1adjectivechinlessHaving a weak jaw, and thought feeble because of it.
“The novel's villain is a chinless aristocrat who has never done a day's work.”
chinless is a quality of appearance.
Chin plus -less. The phrase chinless wonder dates from the mid twentieth century and is British.
Proto-Indo-European
*ǵénus — chin, jaw
Proto-Germanic
*kinnuz — chin
Proto-West Germanic
*kinnu
Old English
ċinn — chin
Middle English
chyn
English
chin
English, today
chinless
From chin + less. chin comes from Middle English chyn, from Old English ċinn (“chin”), from Proto-West Germanic kinnu, from Proto-Germanic kinnuz (“chin”), from Proto-Indo-European ǵénus (“chin, jaw”). Compare West Frisian/Dutch kin, Low German/German Kinn, Danish kind, Icelandic kinn, Welsh gen, Latin gena, xto śanweṃ, Ancient Greek γένυς (“jaw”), Armenian ծնոտ, Persian چانه, Sanskrit हनु. a doublet of gena.
Etymology from Wiktionary, CC BY-SA