Greco-Roman equivalent of 'sari' (or dhoti). Or hagoromo. Outer wear, generally work as a light cloak or wrap over other clothing.
If you see a character wearing Greco-Roman-themed clothes, and there appears to be a long, thin piece of cloth wrapped around the shoulders (and trailing past the waist, hagoromo-style), it is likely a himation.
This tag implicates ancient_greek_clothes (learn more).