'Smooth' in the Bible

Every valley shall be filled, and every mountain and hill shall be brought low; and the crooked shall be made straight, and the rough ways shall be made smooth;

for such people do not serve our Lord Christ but their own appetites. They deceive the hearts of the unsuspecting with smooth talk and flattering words.

For it is common knowledge among you that we never made use of smooth-sounding false words, and God is witness that at no time were we secretly desiring profit for ourselves,

Cut through and make smooth, straight paths for your feet [that are safe and go in the right direction], so that the leg which is lame may not be put out of joint, but rather may be healed.