Actually, if you look up “conservative” in Merriam-Webster (http://www.m-w.com/dictionary/conservative), there’s no mention of limited government or anything similar:
Main Entry: con·ser·va·tism 
Pronunciation: k&n-'s&r-v&-"ti-z&m
Function: noun
1 capitalized a : the principles and policies of a Conservative party b : the Conservative party
2 a : disposition in politics to preserve what is established b : a political philosophy based on tradition and social stability, stressing established institutions, and preferring gradual development to abrupt change
3 : the tendency to prefer an existing or traditional situation to change
So in a society that was already based on limited government, a “conservative” might advocate limited government. But in a society where the government has become essentially unlimited, such as our own, the “conservative” becomes an advocate of unlimited government.
The correct term for the philosophy of limited government (and some may be surprised at this), is not “conservatism” but “liberalism”:
Main Entry: lib·er·al·ism 
Pronunciation: 'li-b(&-)r&-"li-z&m
Function: noun
1 : the quality or state of being liberal
2 a often capitalized : a movement in modern Protestantism emphasizing intellectual liberty and the spiritual and ethical content of Christianity b : a theory in economics emphasizing individual freedom from restraint and usually based on free competition, the self-regulating market, and the gold standard c : a political philosophy based on belief in progress, the essential goodness of the human race, and the autonomy of the individual and standing for the protection of political and civil liberties d capitalized : the principles and policies of a Liberal party
Many years ago, in his seminal book The Road to Serfdom, F. A. Hayek made some wise remarks about conservatism:
“Conservatism . . . is not a social program; in its paternalistic, nationalistic, and power-adoring tendencies it is often closer to socialism than true liberalism; and with its traditionalistic, anti-intellectual, and often mystical propensities it will never, except in short periods of disillusionment, appeal to the young and all those others who believe that some changes are desirable if this world is to become a better place. A conservative movement, by its very nature, is bound to be a defender of established privilege and to lean on the power of government for the protection of privilege. The essence of the liberal position, however, is the denial of all privilege, if privilege is understood in its proper and original meaning of the state granting and protecting rights to some which are not available on equal terms to others.”
I delve into this further at http://www.humanactioncourse.info/pp/cf/HI30018.html.