The dictionary defines evil as, morally wrong; immoral; wicked. It could be something harmful or injurious; the synonyms though may be the best descriptions.
Depending on how it is used evil can be; sinful, iniquitous, depraved, base, vile, nefarious, pernicious, destructive, wickedness, unrighteousness, or corruption, to name a few.
“Now it happened, as He was dining in Levi’s house, that many tax collectors and sinners also sat together with Jesus and His disciples; for there were many, and they followed Him. And when the scribes and Pharisees saw Him eating with the tax collectors and sinners, they said to His disciples, ‘How is it that He eats and drinks with tax collectors and sinners?’ When Jesus heard it, He said to them, ‘Those who are well have no need of a physician, but those who are sick. I did not come to call the righteous, but sinners, to repentance.’” Mark 2:15-17.
“For we did not follow cunningly devised fables when we made known to you the power and coming of our Lord Jesus Christ, but were eyewitnesses of His majesty.” 2 Peter 1:16.
“When it is evening you say, ‘It will be fair weather, for the sky is red’; and in the morning, ‘It will be foul weather today, for the sky is red and threatening.’ Hypocrites! You know how to discern the face of the sky, but you cannot discern the signs of the times.” Matthew 16:2b-3.