In the course of developing a report, essay, memo, etc. writers are often called upon to define their terms.

Ten of the more common types of definitions used in professional and academic writing are:

Aristotelian	explicative		operational
analytical	example		graphical
historical	elimination		etymological
comparitive

From material prepared by:
Professor Merrill Whitburn
The Writing Center
4508 Sage Laboratory
Rensselaer Polytechnic Institute