Lewis Short
ambŭlācrum (noun N) : ambulo
* A walk planted with trees, commonly near a house (only ante-and post-class. for the class. ambulatio), Fest. p. 18: senex Gynaeceum aedificare volt hic in suis Et balineas et ambulacrum et porticum,Plaut. Most. 3, 2, 69: longa et mollia ambulacra, * Gell. 1, 2, 2; Pall. 1, 18, 2.
Charlton T. Lewis, Charles Short, A Latin Dictionary