Abarim Publications' online Biblical Greek Dictionary
The adjective κακος (kakos) means bad or worthless, and is an opposite of words like αγαθος (agathos), meaning good, virtuous or beneficial, and καλος (kalos), meaning good in the sense of pleasant and complete. Our adjective κακος (kakos) refers to disharmony, disturbance or incompleteness, or simply to a waste product: some worthless residual after all beneficial or useful components have been extracted. Note that the Greek word κακκη (kakke) refers to human excrement, and derives from the Proto-Indo-European root kaka-, meaning to defecate.
Despite its modern popularity, bi-polar thought (good versus evil, light versus dark, all that) isn't Biblical. Of course there is good versus bad and light versus dark in the Bible but these are not considered each other's counter-poles. In fact, darkness is not the opposite of light but the absence of it and not the presence of something else. Likewise death is the absence of life but not the presence of something else. Likewise evil and hate are the absences of good and love but not the presences of something else. The highest state of being is that of freedom (Galatians 5:1), because only when a person is free can he both follow God and be wholly responsible for his own actions. The absence of freedom results in bondage and labor: the New Testament word for evil, namely the adjective πονηρος (poneros), comes from the verb πενομαι (penomai), meaning to toil or labor.
Ergo: our adjective κακος (kakos) describes any quality that leads not to freedom but to bondage. It's used 51 times in the New Testament, see full concordance, and from it come:
- Together with the particle of negation α (a), meaning not or without: the adjective ακακος (akakos), literally meaning without badness but in the classics mostly used in the sense of being unaware of any badness. As the saying goes: it takes one to know one, and our word mostly emphasizes a being simple or even gullible (Romans 16:18 and Hebrews 7:26 only).
- Together with the verb ανεχω (anecho), meaning to bear or endure: the adjective ανεξικακος (anexikakos), meaning patient in bearing bad things (2 Timothy 2:24 only).
- Together with the preposition εκ (ek), meaning out or from: the verb εκκακεω (ekkakeo), which literally means to be driven by worthlessness, to shirk. It's used 6 times; see full concordance.
- The noun κακια (kakia), meaning badness. It describes any ugliness, uselessness, counter-productiveness, trouble, waste or even faint-heartedness, cowardice or a reputation thereof. It's used 11 times; see full concordance.
- Together with the noun ηθος (ethos), meaning hangout or behavioral home: the noun κακοηθεια (kakoetheia), which describes a habitually negative attitude, cantankerousness or attitudinal vandalism (Romans 1:29 only).
- Together with the noun λογος (logos), meaning word, which in turn comes from the verb λεγω (lego), meaning to speak: the verb κατολογεω (katalogeo), meaning to talk bad or curse. This verb occurs 4 times; see full concordance.
- Together with the noun παθος (pathos), an experiencing: the verb κακοπαθεω (kakopatheo), meaning to experience badness or to endure hardship. This verb is used 4 times, see full concordance, and from it derive:
- Together with the verb ποιεω (poieo), meaning to do, bring about or make: the adjective κακοποιος (kakopoios), literally meaning trouble-maker, but it should be noted that in the Roman world, trouble-making was considered both an act of treason as well as blasphemy against the state deities, and would be punished by mass-crucifixion of everybody involved. Traditional translations interpret this word as "evildoer", but the evil came from the Roman retaliation rather than the act itself. Our word is used 5 times, see full concordance, and from it derives:
- Together with the verb εργω (ergo), meaning to perform work in a non-civilized environment: the verb κακουργος (kakourgos), meaning to bad-work; to engage in activities that work against the formation or maintenance of a civilized state. This essentially came down to high treason, and in Roman society, a charge of high treason could be earned by not worshipping state deities or helping an escaped slave. This verb is used 4 times; see full concordance.
- Again together with the verb εχω (echo) means to have or hold: the verb κακουχεω (kakoucheo), literally meaning bad-having: having bad things happen to you, or rather being treated badly. This verb occurs only twice in the New Testament, namely in Hebrews 11:37 and 13:3. From it stems:
- Again together with the preposition συν (sun), meaning together or with: the verb συγκακουχεω (sugkakoucheo), meaning to be treated badly together (Hebrews 11:25 only).
- The verb κακοω (kakoo), meaning to do bad, worthless or wasteful, to do harm, to cause trouble. This verb is used 6 times, see full concordance, and from it derives:
- The noun κακωσις (kakosis), meaning ill-treatment, trouble, dire straits (Acts 7:34 only).
- The adverb κακως (kakos), meaning badly, roughly, miserably. This word is often used to describe people who are in a bad way, physically or mentally: the sick, the poorly, the ailing. Often this adverb is used together with the verb εχω (echo) to describe "bad-havers": people who have it bad (in a health sense). It's used 16 times; see full concordance.