U.S. President Donald Trump proclaimed Monday night that he is a nationalist. And he said all Americans should be.

At a rally in support of Sen. Ted Cruz in Texas, the president gave the crowd a lesson on political ideologies.

READ MORE: ‘I’m a nationalist, OK? Nationalist. Use that word, use that word,’ Donald Trump says

“A globalist is a person that wants the globe to do well, frankly, not caring about our country so much,” Trump said. “And you know what? We can’t have that. They have a word, it sort of became old-fashioned, it’s called a nationalist, and I say really, we’re not supposed to use that word.”

But the president declared that he is nationalist, and not afraid to say it.

“You know what I am? I’m a nationalist, OK?” he said. “Nationalist. Use that word, use that word.”

Both nationalism and globalism have complex meanings, which have evolved over time. Here’s a closer look at the two ideologies and why they can be so polarizing.

‘Nationalism’ by definition

According to the Cambridge Dictionary, nationalism means: “A nation’s wish and attempt to be politically independent,” or “a great or too great love of your own country.”

Not exactly a new sentiment

Trump’s nationalism declaration didn’t exactly come as a total surprise.

Throughout his presidency, Trump has championed the interests of the United States over more global concerns, saying he will put “America first.” He has spoken critically of various trade deals and pushed for greater limitations on immigration.

He has also defended the concept of putting his country above others during speeches at the United Nations — an organization which seeks to have a unified global agenda.

And during a February 2017 speech at the National Governors Association, Trump said he is a nationalist “in a true sense.” He noted that he still wants trade between countries.

WATCH: Trump arrives in Davos with ‘America First’ agenda

Why is the term ‘nationalist’ concerning?

Monday night’s comments, nonetheless, were concerning to those who explained that the term nationalist has a troubling connotation often tied to racial bias.

As CNN host Don Lemon explained, the term is a “favorite of the alt-right and is loaded with nativist and racial undertones.”

Most concerning is its link to Adolf Hitler and Nazism. Nationalist sentiment was at a high during Hitler’s rise, as he preached the idea that Germany would become the most powerful country in Europe if his plan prevailed.

It is closely linked with the sentiments of white nationalists, a group who have repeatedly made racist remarks about Mexican immigrants and called for bans on Muslims.

White nationalists also notably rallied in Charlottesville, Va., last August. The protests and counterprotests eventually led to the death of one person.

At the time, Trump said some white nationalists were “very fine people.”

WATCH: Donald Trump tells UN General Assembly, ‘I will always put America First’

That’s why political analyst for The Washington Post, Aaron Blake, said Trump’s use of the term in some ways is “long overdue.”

“In some ways, Trump’s use of the word was long overdue. It very much fits with his political strategy and his entire political ethos,” Blake wrote Tuesday.

“And assuming he keeps using it and it leads to an American renaissance of the word — which tends to be the case with Trump — it will only further divide an already riven country.”

‘Globalism’ by definition

According to the Cambridge Dictionary, globalism means: “The idea that events in one country cannot be separated from those in another and that economic and foreign policy should be planned in an international way.”

A look at Trump’s stance on ‘globalism’

This also isn’t the first time Trump has denounced globalism.

He’s often spoken out against the concept of free trade, and immigrants and refugees without referring to globalism. But he has also directly used the term before.

In a September speech at the UN General Assembly, Trump said Americans “reject globalism.”

“We reject the ideology of globalism, and we embrace the doctrine of patriotism,” he said.

WATCH: United Nations has ‘not lived up to potential,’ Trump says

But like nationalism, the phrase also has a loaded meaning beyond nations working together.

The concept of globalism is often blamed for perpetuating issues such as economic inequality around the world at the hands of organizations such as the International Monetary Fund.

The term “globalist” is also frequently used as a jab at left-leaning leaders, who are accused of not caring about the interests of their own country.

The criticism was made more common by former White House strategist Steve Bannon, who repeatedly vouched for nationalism over globalism.