base pair
unit consisting of two nucleobases bound to each other by hydrogen bonds: either adenine–thymine or guanine–cytosine in natural DNA (additional types occur in RNA)
wobble base pair
RNA base pair that does not follow Watson-Crick base pair rules; guanine–uracil (G-U), hypoxanthine–uracil (I-U), hypoxanthine–adenine (I-A), or hypoxanthine–cytosine (I-C)