A hair style that draws the hair back so that it hangs down in back of the head like a pony's tail WordNet 3.0 & Open English WordNet

A ponytail is a hairstyle in which some, most, or all of the hair on the head is pulled away from the face, gathered and secured at the back of the head with a hair tie, clip, or other similar accessory and allowed to hang freely from that point. Wikipedia

Hairstyle where hair is gathered and secured at the back of the head. Wikipedia Disambiguation

Looser bunch of hair Wikidata

A hairstyle where the hair is pulled back and tied into a single "tail" which hangs down behind the head. OmegaWiki

Hairstyle. Wiktionary (translation)