ظالم
Ẓālim
One who commits injustice (zulm): a wrongdoer or oppressor; the plural is zalimun
What it means
Ẓālim is the one who commits ẓulm, injustice. The plural is ẓālimūn. The Quran uses the word often, as in the verse that closes the rules on divorce: “those who transgress the limits of Allah, they are the wrongdoers” (2:229). It also says that Allah is not unaware of what the wrongdoers do (14:42). The word is used of a person who wrongs others, who wrongs himself by sin, or who commits the gravest wrong of associating partners with Allah. One verse speaks of a group among the believers who wrong themselves (35:32). In English it is rendered as wrongdoer, oppressor or tyrant according to context.
Often misunderstood as
That it means only an oppressor of others, when the Quran also uses it of one who wrongs himself.
Term and Arabic as listed in Ismail al Faruqi, Toward Islamic English (International Institute of Islamic Thought, 1995), p. 38, listed as ẒĀLIM. The definition is restated here.