Deconstruction, associated especially with French philosopher and literary critic Jacques Derrida, grew out of structuralism. But whereas structuralists argued that meaning can be pinned down in a network of signifiers, Derrida argued that meaning is always deferred, pushed back on something else, and therefore never present.
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.