"One-idea" forms are usually short, without strong sectional divisions. They are often a study in how to make the most of one theme or motive over a brief period of time.

Subject- the main theme of the fugue, heard at the outset

Answer- the subject transposed to the dominant key, usually heard when the second voice enters

Real answer- an exact transposition of the subject

Tonal answer- a modified transposition in which 5^th scale degrees in the original subject are transposed down a 5^th rather than down a 4^th, especially if they occur early in the subject. It creates a less abrupt turn to the dominant

Countersubject-counterpoint to the answer (or later possibly subject), as long as this material returns enough to make it recognizable

Link or bridge- a short passage between the completion of the answer and the next subject entrance (in the third voice) to allow a modulation back to I

Exposition- the first part of the fugue, extending from the beginning to the completion of the last voice entrance

Episode- a section in which there are no complete entrances of the subject (or answer)

Stretto- subject entrances which follow each other at a closer time interval than normal

Augmentation, diminution, inversion, retrograde- manipulations of the subject sometimes seen in fugues