Definition of "vulnerable"

In my younger and more vulnerable years my father gave me some advice that I’ve been turning over in my mind ever since. ‘Whenever you feel like criticizing any one,’ he told me, ‘just remember that all the people in this world haven’t had the advantages that you’ve had.’

1925, F[rancis] Scott Fitzgerald, chapter 1, in The Great Gatsby, New York, N.Y.: Charles Scribner’s Sons, published 1953

The elimination of [Roger] Federer after [Rafael] Nadal's loss to Lukas Rosol would have created mild panic among the fans of these gloriously gifted but now clearly vulnerable geniuses.

2012 June 29, Kevin Mitchell, “Roger Federer back from Wimbledon 2012 brink to beat Julien Benneteau”, in The Guardian‎, archived from the original on 15 November 2016

One particularly damaging, but often ignored, effect of conflict on education is the proliferation of attacks on schools […] as children, teachers or school buildings become the targets of attacks. Parents fear sending their children to school. Girls are particularly vulnerable to sexual violence.

2013 July 19, Mark Tran, “Denied an education by war”, in The Guardian Weekly, volume 189, number 6, page 1