So you don't get confused, the definition of a grandaunt *is* great-aunt. They are the same. Usage varies on a regional basis, e.g., in the southeast typically "great-aunt" is the more common usage while in the northeast the use of "grandaunt" is more common. There is also regional differences in the prounciation of the word "aunt", in some it is "ant" (like the insect), in others it is "änt" (like ah'nt). Eitheris correct.