(Largely adapted from The Norton Introduction to Literature, Shorter Fifth Edition and M. H. Abrams' A Glossary of Literary Terms, Third Edition)

It should be remembered that these terms are not easily defined. What you find below are helpful "starting points," but most of these terms have multi-layered meanings that make them difficult to define simply.
 

Allegory
a narrative in which the agents and action — and sometimes the setting as well — are contrived not only to make sense in themselves, but also to signify a second, correlated order of persons, things, concepts, or events

Allusion
a reference in a story to history, the Bible, literature, painting, music, and so on, that suggests the meaning or linkage of details in a story to another artistic or non-fiction work

Ambiguity
the ability to mean more than one thing

Antagonist
an important character who is pitted against the chief character of a work

Archetype
a plot or character element that recurs in cultural or cross-cultural myths

Burlesque
often defined as ‘an incongruous imitation'; that is, it imitates the matter or manner of a seriousliterary work, or literary genre, but makes the imitation amusing by a ridiculous disparity between its form and style and its subject matter

Central Narrator or Central Consciousness
a limited point of view used to tell a story, one tied to a single character throughout the story, often with access to his or her inner thoughts (but not to the thoughts of others)

Elegy
a formal and sustained poem of lament for the death of a particular person

Epiphany
a sudden revelation of an ordinary object or scene

Figurative
non-literal; implicitly or explicitly representative of something in terms of some other unlike thing that seems to be similar or analogous

Hero/Heroine
the chief character of a work, or a character that the author holds up as the best example of certain cherished values and behaviors

Irony
a statement or plot which has an implicit meaning intended by the speaker which differs from that which the speaker ostensibly asserts

Leitmotif (pronounced: "lite-mo-teef")
an element that is frequently repeated in a work and often serves as a guiding or central element within the work

Metaphor
an implicit comparison or identification of one thing with another unlike itself without the use of a verbal sign (such as "like" or "as"= a simile will use the construction "like" or "as")

Motif
an element — a type of incident, device, or formula — which recurs frequently in literature

Myth
like allegory, myth usually is symbolic and extensive, including an entire work or story; though it no longer is necessarily specific to a single culture and pervasive in that culture — individual authors may now be said to create myths — there is still a sense that myth is communal or cultural, while the symbolic can often be private and personal

Naturalism
a school of writing that concentrates on writing in a way that reflects life as it seems to the common reader, but backed by the philosophical stance (rooted in post-Darwinian biology) that humans belong entirely in the order of nature and do not have a soul or any other connection with a religious or spiritual world beyond nature.  Humans are therefore merely a higher-order animal whose character and fortunes are determined by two kinds of natural forces: heredity and environment.

Omniscient Narrator or Omniscient Point of View
a perspective that can tell the story from one character's view, then another's, then another's or can be moved in or out of any character at any time

Pastoral
a piece, often a poem, that expresses an urban writer's nostalgic image of the peace and simplicity of the life of shepherds and other rural folk in an idealized natural setting

Pathos
a deep feeling attributed to a scene or passage specifically designed to evoke the emotions of tenderness, pity or sympathetic sorrow from the reader

Personification
treating an abstraction as if it were a person, endowing it with human-like qualities

Picaresque Narrative
a genre which emerged in sixteenth-century Spain, the typical picaresque narrative centers on the escapades of an carefree rascal who lives by his wits and shows little if any alteration of character through a long succession of adventures

Point of View
the angle from which the people, events, and other details in a story are viewed

Protagonist
chief character of a work, on whom the reader's interest centers

Realism
a writing style that represents life in literature, which is bent on giving the illusion that it reflects life as it seems to the common reader. The subject of realism is rendered in such a way as to give the reader the illusion of actual experience.

Romance
a writing style that desires its actions and characters not so much to be thought of as realistic, as they are to represent universal categories that transcend the limitations of any specific historical moment

Sentimentalism
in a general sense (and often used pejoratively), this term refers to an excess of emotion to an occasion, or, in a more limited sense, to an overindulgence in the ‘tender' emotions of pathos and sympathy

Simile
a figure that explicitly expresses the comparison, often signaled by "like" or "as"

Symbol
a person, place, thing, event, or pattern in a literary work that designates itself and at the same time figuratively represents or "stand for" something else.  Often the thing or idea represented is more abstract, general, non- or super-rational; the symbol more concrete and particular.

Theme
a generalized, abstract paraphrase of a central or dominant idea found in a story

Tone
the general attitude or feeling a story or a portion of a story takes toward a subject

Traditional symbols
symbols that, through years of usage, have acquired an agreed-on significance, an accepted meaning

Tragic flaw
a trait (usually beyond the character's ability to control) that causes a character's death or demise

Voice
the acknowledged or unacknowledged source of the words of the story; the "speaker;" the "person" telling the story