sheath dress
US /ˈʃiːθ dres/
UK /ˈʃiːθ dres/

1.
a close-fitting dress, typically simple and without a waist seam
:
•
She wore a classic black sheath dress to the cocktail party.
•
The tailor expertly fitted the sheath dress to her figure.
a close-fitting dress, typically simple and without a waist seam