noun
BAD : On almost every page there were announcements for cigarettesand tobacco.
GOOD : On almost every page there were advertisements for cigarettes and tobacco.
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When you want to give people some important information, you make an announcement : 'Following the announcement of their marriage, they were pursued by crowds of journalists.'
An advertisement is an item in a newspaper, on television, etc, that tries to persuade people to buy something, apply for a job, etc: 'At this time of the year, the papers are full of holiday advertisements.'