I know there will be 3 translational D.O.F. and 3 rotational D.O.F., and It can have 4 vibrational D.O.F. 2(one potential and one kinetic) for each O-H Bond. but from where does 2 more D.O.F. come from? (I am also not sure about the 4 vibrational D.O.F that I talked about is it really 4 or not well it should be but when I searched on internet regarding this it showed that 6 Vibrational D.O.F. in water vapor are asymmetric, symmetric, wagging, twisting, scissoring and rocking. I don't know the meaning of each term so please also explain that).