Concise Bible Dictionary:
Any small particle or splinter. It is used to illustrate small failings in contrast to larger faults, called “beams.” The Lord Jesus was exposing the hypocrisy of those who see and magnify small faults in others, and pass over greater ones in themselves (Matt. 7:3-5; Luke 6:41-42).
Strong’s Dictionary of Greek Words:
Meaning:
from κάρφω (to wither); a dry twig or straw