A widow - This is a circumstance that gives increasing interest to the parable. Judges were bound to show special attention to widows, Isaiah 1:17; Jeremiah 22:3. The reason of this was that they were defenseless, were commonly poor, and were liable to be oppressed by those in power.
Avenge me - This would have been better translated, “Do me justice against my adversary, or vindicate me from him.” It does not denote vengeance or revenge, but simply that she wished to have “justice” done her - a thing which this judge was “bound” to do, but which it seems he had no disposition to do.
Adversary - One opposed in law. In this case it seems that the judge was unwilling to do justice, and probably took advantage of her condition to oppress her.