phrasal
1. : near the permitted, accepted, or tolerable limit of what can be said or done: as
a. : verging on the border line between decency and indecency
jokes that were embarrassingly near the knuckle
b. : verging on what is offensive or injurious to one's sensibilities
accusations too near the knuckle for them to ignore
2. : near to what is of greatest importance, interest, or concern
the real reasons for doing this are, perhaps, nearer the knuckle than they think — John Holloway