"= mobile", Late 16th cent.; earliest use found in William Watson (?1559–1603), Roman Catholic priest and conspirator. From classical Latin mōbile vulgus the changeable common people, the fickle crowd from mōbile, neuter of mōbilis + vulgus.[mobile vulgus etymology, mobile vulgus origin, 英语词源]
"So as to win over or capture the minds and attention of the mass of ordinary people", Early 18th cent. From post-classical Latin ad captandum vulgus from classical Latin ad + captandum, neuter of the gerundive of captāre to entice, allure + vulgus.