A compound word made up of the words hag and ugly, it is used to describe a person, typically a girl, who in addition to being ugly, also has numerous hag-like qualities, such as a cackling laugh, and facial features that go beyond the mere ugly to downright deformed.
Man 1: Hey man, I heard you fucked that Becca chick... bad luck dude, that girl is ugly.
Man 2: Look who's talking, you fucked Milly, that girl is downright Hagley.
Man 1: The shame.
From the Latin, hagleius pulcherus, brought to Britain in AD 55 with Caesar's invasion.
Meaning 'superlative beauty' and is only used in the modern day to signify someone of extreme magnetism and worth.
"Milly is a top-class hagley"