Mavity

In the special edition of Doctor Who that was released on Disney Plus, the TARDIS ends up being exploded by Donna who spilled coffee all over the controls which started a fire, the TARDIS started to have a malfunction and traveled back in time to where ‘Gravity’ was created by Isaac Newton, both Donna and the Fourteenth doctor had a little char with him before Donna gave a little hint about ‘Gravity’ when they both left, Issac Newton started thinking of a name for ‘Gravity’ and ended up naming it ‘Mavity’ instead which carries onto the next specials.

DONNA: Still, wherever we are, could be worse. We've got air, we've got light, we've got mavity.
DOCTOR: Yeah.
DONNA: Was it me, or was Isaac Newton hot?
DOCTOR: He was, wasn't he? He was so hot. Oh! Is that who I am now?