1. To occur at the same time; to coincide in point of time; to be contemporary or simultaneous: The couple tried to synchronize their work schedule so that they could go on vacation together.
2. To cause to be, or represent as, synchronous; to assign the same date to; to bring together events, etc. belonging to the same time: Mr. and Mrs. Smith got out their date books in order to synchronize the important events they had to organize.
3. To occur at the same successive instants of time; to keep time with; to go on at the same rate and exactly together; to have coincident periods as two sets of movements or vibrations: The conductor of the chamber orchestra wanted all the strings to synchronize their bowing so as to keep the exact tempo of the piece.
4. To cause to go at the same rate, specifically to cause (a timepiece) to indicate the same time as another: The two girls synchronized their watches before going rock climbing in the Alps.
5. In technical senses: to cause to coincide in time; to operate simultaneously: The coordinator tried to synchronize the activities at school, but it didn't work out, and everything took much longer than expected.