(noun)
Metaphorical phrase; concieved, most likely, by proud fan-girling Tumblr users, to express a powerful sexual reaction towards a display of devastatingly impressive bone structure - with particular emphasis and interest to the pronounced, and often vertiginious, zygomatic bone cheekbone area.
'Benedict Cumberbatch as 'Sherlock' gives me a major cheekboner' *ovaries explode*
'I dreamt about Cillian Murphy last night and woke up with a cheekboner'
'Johnny Depp in 'Cry Baby'. Cheekboner, anybody?! *sharp inhale of breath*