A cutting tool fastener having a rotation axis and configured to secure together, and establish a fluid path between, two cutting tool members, while also accommodating angular and pivotal displacement between the two. The fastener comprising a head with at least one head opening for emitting fluid, and a body which extends from the head and has a body opening for receiving fluid to be emitted via the head opening. The head has a spherical head abutment surface with a bottom spherical seal surface zone. At least a portion of the spherical head abutment surface faces the body, and the head opening opens out to the spherical head abutment surface. The bottom spherical seal surface zone is axially located between the body and the head opening.