The word you are probably thinking of is "majoritarianism"
It is the implied assumption in many political arguments that
the majority has the right to control the entirety of society in
some way or another. It is a slight problem for democracies, and
there are usually some laws which prevent majoritarianism becoming
a problem. For instance, more radical changes often involve a 75%
vote as a necessity, and some countries do not allow certain laws
to be passed regardless of the vote.
The best example of this would be the US, which has a
constitution (along with amendments) preventing congress from
making certain laws. For instance, congress cannot pass any law
which would hinder freedom of religion. This counters
majoritarianism because even if 99% of Americans wanted to outlaw a
certain religion, they would be unable to do so.