Duplicate Content
Content which is duplicate or near duplicate in nature.Search engines do not want to index multiple versions of similar content. For example, printer friendly pages may be search engine unfriendly duplicates.

Duration
The weighted-average life of the present value of all future cash flows, both principal and interest, of a security. It is used as a measure of the sensitivity of the value of a security to changes in interest rates.

Dynamic
Information, content, or data generated 'on-the-fly' from a database. Also see "database-driven."