Imperfectum

Imperfectum (Latin "unfinished" or "incomplete") may mean:
 * Imperfect, a verb form
 * Opus Imperfectum, an early Christian commentary on the Gospel of Matthew
 * in the Middle Age theory of music
 * for tempi - tempus imperfectum and tempus imperfectum diminutum - see Mensural notation
 * for consonances see Consonance and dissonance