Answer:

xyst

Answer	Crossword Clue
XYST	Ancient Greek promenade
XYST	Anc. Grecian promenade
XYST	Portico of ancient Rome.

XYST	Greek promenade
XYST	Roman portico
XYST	Ancient portico
XYST	Greek portico

Crossword

a puzzle consisting of a grid of squares and blanks into which words crossing vertically and horizontally are written according to clues.