Why is the word "democracy" not in the preamble of the US Constitution?

Why? Try these on for size:

Meanwhile, when the Democratic Party formed in 1828, it was with a Tory outlook keen on robbing others of their rights:

—John Adams

Can a mother forget her child after she puts him or her up for adoption?

The republican is the only form of government which is not eternally at open or secret war with the rights of mankind.

To Indians: “Pack up what belongings you can carry and start walking to Oklahoma. Your fertile lands are ours now. We voted fair and square and your side lost.”

Majority-rules democracy is the way that majorities run roughshod over minorities, destroying rights and all ideas of equality under the law. No fair-minded person wants anything to do with democracy.

What do gang stalkers want?

—Benjamin Franklin

When the people find they can vote themselves money, that will herald the end of the republic.

In other words, our Founding Fathers and other Whig intellects of that time well understood that democratic methods are the surefire means to do serious damage to the rights guaranteed under republican self-government.

Trump is going to target known criminals in the country illegally for deportation. The Democrats have vowed to fight him every step of the way. Don't they understand this is one of the issues that cost them the white house, the house and senate?

I do not say that democracy has been more pernicious on the whole, and in the long run, than monarchy or aristocracy. Democracy has never been and never can be so durable as aristocracy or monarchy; but while it lasts, it is more bloody than either.

—Thomas Jefferson

To blacks: “You can’t drink from that water fountain… eat in this cafeteria… ride this bus… go to this school. We voted fair and square and your side lost.

How do military families balance personal political views with respect for civilian leadership?

Another tendency, which is extremely natural to democratic nations and extremely dangerous, is that which leads them to despise and undervalue the rights of private persons.

[with republicanism being the rights-protecting form of governance afforded us by our Constitution]

—Alexis de Tocqueville

Why does everyone hate Anthony Joshua so much? I get that he isn’t the best heavyweight boxer ever but people claim he’s a no skill fighter but he has an Olympic gold medal, a world championship, and beat Klitschko, a dominant force in boxing

To slaves: “You can forget your notions of freedom. We voted fair and square and your side lost.”