casual hairstyle; loose hair
Refers to hair worn down or loosely tied in a casual, informal style, often contrasted with formal updos.
I went out with my hair down today.
パーティーには散らし髪よりアップスタイルの方が合う。
An updo suits a party better than a casual loose hairstyle.
Compound of 散らし (scattering, from 散らす) and 髪 (hair), referring to hair that is not tightly bound.