
You have to look at the hands – it always gives an onychophagist away…
Deriving from the Greek ‘onux’ – a nail or claw, plus ‘– phagia’ which means eating or devouring, it refers to individuals who consider their nails a rare delicacy. The main enemies of onychophagists are moms – who fight a continuous battle against their kids (the biggest practitioners of onychophagy) to ‘stop biting their nails!’
Source: World Wide Words