What are worthless and wicked people like? They are constant liars. Proverbs 6:12 (NLT)
The etymology of the word is often understood as "lacking worth", from two common words: beli- (בְּלִי "without-") and ya'al ( יָעַל "to be of value").
Ah, you destroyer, who yourself have not been destroyed, you traitor, whom none has betrayed! When you have ceased to destroy, you will be destroyed; and when you have finished betraying, they will betray you. - Isaiah 33:1 (ESV)
Image: 'Enter Scorpius' by Al Wiggins Jr.