Correct definition for syncopation is

The correct definition of "syncopation" is "placing an accent on a weak beat or between beats"

In music, syncopation involves a variety of rhythms which are in some way unexpected, making part or all of a tune or piece of music off-beat. More simply, syncopation is "a disturbance or interruption of the regular flow of rhythm": a "placement of rhythmic stresses or accents where they wouldn't normally occur."