Jamieson, Fausset and Brown on Ezekiel 19:7

7. knew ... desolate palaces--that is, claimed as his own their palaces, which he then proceeded to "desolate." The Hebrew, literally "widows"; hence widowed palaces (Is 13:22). Vatablus (whom Fairbairn follows) explains it, "He knew (carnally) the widows of those whom he devoured" (Eze 19:6). But thus the metaphor and the literal reality would be blended: the lion being represented as knowing widows. The reality, however, often elsewhere thus breaks through the veil.

fulness thereof--all that it contained; its inhabitants.