IMDB genre definitions

Action	Should contain numerous scenes where action is spectacular and usually destructive. Note: if a movie contains just one action scene (even if prolonged, e.g., airplane-accident) it does not qualify. Subjective.
Adventure	Should contain numerous consecutive and inter-related scenes of characters participating in hazardous or exciting experiences for a specific goal. Not to be confused with Action, and should only sometimes be supplied with it. Subjective.
Biography	Primary focus is on the depiction of activities and personality of a real person or persons, for some or all of their lifetime. Events in their life may be reenacted, or described in a documentary style. If re-enacted, they should generally follow reasonably close to the factual record, within the limitations of dramatic necessity. A real person in a fictional setting would not qualify a production for this genre. If the focus is primarily on events, rather than a person, use History instead.
Comedy	Virtually all scenes should contain characters participating in humorous or comedic experiences. The comedy can be exclusively for the viewer, at the expense of the characters in the title, or be shared with them. Please submit qualifying keywords to better describe the humor (i.e. spoof, parody, irony, slapstick, satire, black-comedy etc). If the title does not conform to the 'virtually all scenes' guideline then please do not add the comedy genre; instead, submit the same keyword variations described above to signify the comedic elements of the title. Subjective.
Crime	Should contain numerous consecutive and inter-related scenes of characters participating, aiding, abetting, and/or planning criminal behavior or experiences usually for an illicit goal. Not to be confused with Film-Noir, and only sometimes should be supplied with it. Subjective.
Drama	Should contain numerous consecutive scenes of characters portrayed to effect a serious narrative throughout the title. This can be exaggerated upon to produce melodrama. Subjective.
Family	Should be universally accepted viewing. e.g., aimed specifically for the education and/or entertainment of children or the entire family. Note: Usually, but not always, complementary to Animation. Objective.
Fantasy	Should contain numerous consecutive scenes of characters portrayed to effect a magical and/or mystical narrative throughout the title. Note: not to be confused with Sci-Fi which is not usually based in magic or mysticism. Subjective.
Film-Noir	Should be shot in black and white, American, and set in contemporary times (relative to shooting date). We take the view that this genre began with Underworld (1927) and ended with Touch of Evil (1958). Note: neo-noir should be submitted as a keyword instead of this genre for titles that do not fit all criteria. Objective.
Horror	Should contain numerous consecutive scenes of characters effecting a terrifying and/or repugnant narrative throughout the title. Note: not to be confused with Thriller which is not usually based in fear or abhorrence. Subjective.
Musical	Should contain several scenes of characters bursting into song aimed at the viewer (this excludes songs performed for the enjoyment of other characters that may be viewing) while the rest of the time, usually but not exclusively, portraying a narrative that alludes to another Genre. Note: not to be added for titles that are simply music related or have music performances in them; e.g., pop concerts do not apply. Also, classical opera, since it is entirely musical, does not apply and should instead be treated as Music. Objective.
Mystery	Should contain numerous inter-related scenes of one or more characters endeavoring to widen their knowledge of anything pertaining to themselves or others. Note: Usually, but not always associated with Crime. Subjective.
Romance	Should contain numerous inter-related scenes of a character and their personal life with emphasis on emotional attachment or involvement with other characters, especially those characterized by a high level of purity and devotion. Note: Reminder, as with all genres if this does not describe the movie wholly, but only certain scenes or a subplot, then it should be submitted as a keyword instead. Subjective.
Sci-Fi	Numerous scenes, and/or the entire background for the setting of the narrative, should be based on speculative scientific discoveries or developments, environmental changes, space travel, or life on other planets. Subjective.
Thriller	Should contain numerous sensational scenes or a narrative that is sensational or suspenseful. Note: not to be confused with Mystery or Horror, and should only sometimes be accompanied by one (or both). Subjective.
War	Should contain numerous scenes and/or a narrative that pertains to a real war (i.e., past or current). Note: for titles that portray fictional war, please submit it as a keyword only. Objective.
Western	Should contain numerous scenes and/or a narrative that portrays frontier life in the American West during 1600s to contemporary times. Objective.  I decided to research genres as its one of the most important parts in media, media involves film making and genres are needed when films are made so its vital for me to know about genre definitions because me and my group will be creating a oppening sequence and will need an idea of what genre the oppening sequence is going to be. These genre definitions have been copied off the imbd website.