Dissociate and its synonym disassociate can both mean "to separate from association or union with another." Associate is from Latin ad-, meaning "to," and sociare, meaning "to join." Dis- in this case means "do the opposite of," so both dissociate and disassociate indicate severing that which is united. Some commentators, however, argue that disassociate is illogical because it indicates separating and uniting simultaneously. Dissociate is slightly older, appearing in the late 16th century, whereas early evidence of disassociate is found in the beginning decade of the next century. Dissociate is recommended by a number of commentators on the basis that it is shorter, which it is by a grand total of two letters—not the firmest ground for an endorsement. Both words are in current good use, but disassociate is used more often in the U.S.