loose-tongued

To him her face was its confutation, and he knew how loose-tongued is calumny; but still—!

I sounded him some weeks ago, and found him too loose-tongued for our purposes.

Charles was troubled when he heard the story of his loose-tongued guide.

Now she turned her accusing glance on the loose-tongued girl.

He was not one of the loose-tongued sort, who tell all to everybody.