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

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

Why? Try these on for size:

—John Adams

Why cant I feel anything in my sleep? I cannot even feel myself moving, breathing, and swallowing saliva! I cannot even hear anything, not even my alarm! Some people that I've been with says that I'm moving a lot in my sleep, how can I stop it?

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.

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.

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.

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—Alexis de Tocqueville

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

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.”

My parents force me (15yo atheist) to go to church, and there’s this thing called Small Sundays where we discuss the Bible in groups, there are questions asked about the Bible. What am I supposed to do when they ask?

—Thomas Jefferson

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

—Benjamin Franklin

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

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.

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.

Bond Yields Keeping Climbing. Governments Can Bring Them Down. - Barron's

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