This process Derrida calls différance, a portmanteau word combining the ideas of difference and deferral. Meaning is always put off, never immediately available. Moreover, ideas are always implicated in their opposites. Binary oppositions black and white, master and slave, beauty and ugliness are defined in terms of their opposites, and neither pole has meaning without the other.
Deconstruction is notoriously complex, and is very badly served by a brief glossary entry. Many of its practitioners do little to make it easy for you: their prose style can be extremely dense. M. H. Abrams offers a good, clear discussion in a few pages in his Glossary of Literary Terms. A more thorough introduction is Jonathan Culler's On Deconstruction.
Note: This guide is still in the early stages of development.
Three question marks mean I have to write more on the subject. Bear with me.