From ek and klino; to deviate, i.e. (absolutely) to shun (literally or figuratively), or (relatively) to decline (from piety) -- avoid, eschew, go out of the way.
KJV: Now I beseech you, brethren, mark them which cause divisions and offences contrary to the doctrine which ye have learned; and avoid them.
NASB: Now I urge you, brethren, keep your eye on those who cause dissensions and hindrances contrary to the teaching which you learned, and turn away from them.