deconstruction: the strategy of textual interpretation advocated by Jacques Derrida and followed by Paul de Man, Jonathan Culler and countless others. It focuses on showing what the text omits or represses: how it collapses in on itself or displays its own contingency etc. It was far more popular in literature than in philosophy departments in the English-speaking academy.
differance: Derrida's mysterious misspelling of 'difference.' The notion derives from Saussure's insight that language is a system of differences. "Now, how am I to speak of the a of differance? It is clear that it cannot be exposed. . . . if differance is (I also cross out the is) what makes the presentation of being-present possible, it never presents itself as such. . . Any exposition would expose it to disappearing as a disappearance."
genealogy: a history of concepts or truths, coined by Nietzsche in his book Genealogy of Morals, which showed how Western moral notions emerged from resentment toward the healthy and powerful. The greatest practitioner of genealogy was Foucault.
hermeneutics: the study of textual interpretation. 'Hermeneutics' at one time was used mainly with regard to Biblical interpretation (especially the 19th-century work of Schleiermacher). It has also come to indicate a kind of mellow pomo or post-Heidegger philosophy associated with Hans-Georg Gadamer that took textual interpretation as a model for how we experience the world as a whole.
meta-narrative: a narrative is a story, more or less. In Lyotard's influential treatment of post-modernism, a meta-narrative is a big story used to organize history or culture as a whole, as in the inevitable march of freedom or the story of class struggle ending in utopia etc.
Other: the apparently empty category that defines the positive category by exclusion: woman, the primitive, etc.
semiotics or semiology: the study of signs, especially linguistic signs. Probably coined by C.S. Peirce, but associated by post-modernism with the linguistics of Saussure.
simulacrum: an item that is a simulation or model of another, as a picture, for example. The plural is simulacra. In the thought of Baudrillard, the post-modern era is the era of the "precession of simulacra" in which all originals have disappeared and we live in an infinite circulation of signs without originals.
structuralism: an approach to the human sciences that focuses on intra-cultural conceptual systems rather than on, say, sheer adaptation of organism to environment etc. The approach is especially associated with the anthropology of Levi-Strauss, and focuses on such things as the structure of kinship and linguistic systems. The philosophy especially of Derrida and Foucault came to be called post-structuralism: it was influenced by structuralism, but took its insights in radical directions, often exposing the contradictions or tensions in these systems, or "deconstructing" them.
sub-altern: oppressed or subordinated, in virtue of one's membership in or assignment to a group.