Jamieson, Fausset and Brown on James 3:8

8. no man--literally, "no one of men": neither can a man control his neighbor's, nor even his own tongue. Hence the truth of Jas 3:2 appears.

unruly evil--The Greek, implies that it is at once restless and incapable of restraint. Nay, though nature has hedged it in with a double barrier of the lips and teeth, it bursts from its barriers to assail and ruin men [Estius].

deadly--literally, "death-bearing."