Dictionary.com

Systematic

1. having, showing, or involving a system, method, or plan: a systematic course of reading; systematic efforts.
2. given to or using a system or method; methodical: a systematic person.
3. arranged in or comprising an ordered system: systematic theology.
4. concerned with classification: systematic botany.
5. pertaining to, based on, or in accordance with a system of classification: the systematic names of plants.

Theology

See the following: Theology Part 1, Part 2, Part 3

Etymonline.com

1670s, “pertaining to a system,” from French systématique or directly from Late Latin systematicus, from Greek systematikos “combined in a whole,” from systema (genitive systematos); see system. From 1789 as “methodical,” often in a bad sense, “ruthlessly methodical.” Related: Systematical (1660s); systematically.

Discussion/Explanation

From Google’s dictionary:

“noun: systematic theology – a form of theology in which the aim is to arrange religious truths in a self-consistent whole.”

This fairly well gets at the gist of this area of study. The point is not to represent the theology of the Bible as a redemptive whole (which is more the realm of Biblical Theology) but to connect things together from the various books of the Bible.

This area of study is much more preoccupied with organizing the information of the Bible into various categories. It is through such efforts that you get subareas like angelology, demonology, pneumatology (study of the Holy Spirit), eschatology (study of the end times, and so on. It addresses individual topics one by one.

It is considered systematic in that it links the various pieces of information found throughout the Scriptures on the particular topic together.

Systematic theology is also one of the main four branches of theology which include exegetical theology, practical theology, and historical theology.