great-aunt (n.)

word-forming element denoting "kinship one degree further removed," early 15c. (in great uncle), from great (adj.), based on similar use of French grand (see grand-). An Old English way of saying "great-grandfather" was þridda fæder, literally "third father;" in early Middle English furþur ealdefader was used (12c.).

"sister of one's father or mother," c. 1300, from Anglo-French aunte, Old French ante (Modern French tante, from a 13c. variant), from Latin amita "paternal aunt" diminutive of *amma a baby-talk word for "mother" (source also of Greek amma "mother," Old Norse amma "grandmother," Middle Irish ammait "old hag," Hebrew em, Arabic umm "mother").

Extended senses include "an old woman, a gossip" (1580s); "a procuress" (1670s); and "any benevolent woman," in American English, where auntie was recorded since c. 1790 as "a term often used in accosting elderly women." The French word also has become the word for "aunt" in Dutch, German (Tante), and Danish.

Swedish has retained the original Germanic (and Indo-European) custom of distinguishing aunts by separate terms derived from "father's sister" (faster) and "mother's sister" (moster). The Old English equivalents were faðu and modrige. In Latin, too, the formal word for "aunt on mother's side" was matertera. Some languages have a separate term for aunts-in-law as opposed to blood relations.