Definition:  Latin for creation [or created] afresh.

More about the term:  Progressive creationism sees the creative work of God as a combination of a series of de novo creative acts and an immanent or processive operation.  God at several points, rather widely separated in time, created de novo.  On these occasions he did not make use of previously existing life, simply modifying it.  While he might have brought into being something quite similar to an already existing creation, there were a number of changes and the product of his work was a completely new creature.  Notice that this is completely compatible with common descent evolution and intelligent design.  This isn’t Darwinism but it may be accurate to say that creatio de novo is a categorically acceptable position for theistic evolutionists.  God takes preexisting forms and adds information to that form to have a creation de novo.

For more on this please see Millard Erickson’s Christian Theology ed 2; Hugh Ross’ A Matter of Days; and Fuz Rana’s Who Was Adam?