The term moderate is used to describe a political view that is neither consistently conservative nor liberal. RINOs will sometimes refer to themselves as "moderate conservatives". In an attempt to deceive viewers into believing that their beliefs are in line with what "average" Americans believe, the liberal media will also use the term "moderate" as a more popular label for themselves and their friends. Often, moderate politicians accept abortion and same-sex marriage.
Historically in France, moderates were a middle-of-the-road political faction or group during the French Revolution. The French National Assembly established a constitutional monarchy and, in 1791, adopted a new constitution that created a Legislative Assembly. Three factions quickly formed in the new Legislative Assembly, known as the radicals (liberals), moderates (centrists) and Conservatives, similar to those political movements today in the United States.
The three factions sat in different sections of the large assembly hall, with the radicals (liberals) sitting on the left, the moderates sitting in the center, and the Conservatives sitting on the right. That gave rise to the left-center-right terminology that we still use today in the United States to describe these three political groups.
The number of people who consider themselves moderates in the United States historically ouweighed those who consider themselves liberal or conservative, and that number remained constant since the middle 1970s. A more recent Gallup poll from 2009 showed that that has changed, though, and more people identify as conservative now. 
Quotes about Moderates
"I would remind you that extremism in the defense of liberty is no vice. And let me remind you also that moderation in the pursuit of justice is no virtue."-Barry Goldwater
God's position on "Moderates"
"“‘I know your works: you are neither cold nor hot. Would that you were either cold or hot! So, because you are lukewarm, and neither hot nor cold, I will spit you out of my mouth.-Revelation 3:15-16  (see also Conservapedia Bible Project)