'Thickly' in the Bible

Running and charging headlong against HimWith his ornamented and massive shield;

Then you will know [without any doubt] that I am the Lord, when their slain are among their idols around their altars, on every high hill, on all the tops of the mountains, under every leafy tree and under every oak with thick branches, the places where they offered sweet incense and a soothing aroma to all their idols.