A cutting tool fastener having a rotation axis and configured to secure together, and establish a fluid path between, two cutting tool members (16, 18), while also accommodating angular and pivotal displacement between the two, the fastener comprising: a head comprising a head peripheral surface having at least one head opening for emitting fluid; and a body extending from the head and comprising: a body peripheral surface; a body opening for receiving fluid to be emitted via the head opening; an internal fastener fluid channel extending at least partially along the rotation axis and in fluid-communication with the head and body openings (34, 50); and top sealing means (38, 32, 33) configured for providing fluid seal, the top sealing means (38, 32, 33) being located at the head, axially above the head opening and away from the body; characterised in that: the head peripheral surface comprises a spherical head abutment surface, at least a portion of which faces towards the body; the spherical head abutment surface comprises a bottom spherical seal surface zone; the head opening opens out to the spherical head abutment surface; and the bottom spherical seal surface zone is axially located between the body and the head opening. a head comprising a head peripheral surface having at least one head opening for emitting fluid; and a body extending from the head and comprising: a body peripheral surface; a body opening for receiving fluid to be emitted via the head opening; an internal fastener fluid channel extending at least partially along the rotation axis and in fluid-communication with the head and body openings (34, 50); and top sealing means (38, 32, 33) configured for providing fluid seal, the top sealing means (38, 32, 33) being located at the head, axially above the head opening and away from the body; characterised in that: the head peripheral surface comprises a spherical head abutment surface, at least a portion of which faces towards the body; the spherical head abutment surface comprises a bottom spherical seal surface zone; the head opening opens out to the spherical head abutment surface; and the bottom spherical seal surface zone is axially located between the body and the head opening. a body peripheral surface; a body opening for receiving fluid to be emitted via the head opening; an internal fastener fluid channel extending at least partially along the rotation axis and in fluid-communication with the head and body openings (34, 50); and top sealing means (38, 32, 33) configured for providing fluid seal, the top sealing means (38, 32, 33) being located at the head, axially above the head opening and away from the body; characterised in that: the head peripheral surface comprises a spherical head abutment surface, at least a portion of which faces towards the body; the spherical head abutment surface comprises a bottom spherical seal surface zone; the head opening opens out to the spherical head abutment surface; and the bottom spherical seal surface zone is axially located between the body and the head opening. the head peripheral surface comprises a spherical head abutment surface, at least a portion of which faces towards the body; the spherical head abutment surface comprises a bottom spherical seal surface zone; the head opening opens out to the spherical head abutment surface; and the bottom spherical seal surface zone is axially located between the body and the head opening.