Millions of illegals continue nationwide marches, angrily demanding "their rights" and indimidating our own elected politicians who are supposed to represent the rights of legal Americans. Could these marches be looked at as a form of domestic "terrorism" ?

I agree that there is no blatant violence per se but this still fits the various definitions for "terrorism" posted online in dictionaries and other sources.

Terrorism: "The unlawful use or threatened use of force or violence by a person or an organized group against people or property with the intention of intimidating or coercing societies or governments, often for ideological or political reasons."

“One man’s terrorist is another man’s freedom fighter,”

"terrorist • a person who uses violence and intimidation in the pursuit of political aims."

"Interestingly, the American definition of terrorism is a reversal of the word's original meaning, given in the Oxford English Dictionary as "government by intimidation". Today it usually refers to intimidation of governments."

"The United States defines "international terrorism" as activities that:
1. involve violent acts or acts dangerous to human life that are a violation of the criminal laws of the United States or of any State, or that would be a criminal violation if committed within the jurisdiction of the United States or any State;
2. appear to be intended:
a. to intimidate or coerce a civilian population;
b. to influence the policy of a government by intimidation or coercion; or
c. to affect the conduct of a government by assassination or kidnapping; and
3. occur totally outside the United States, or transcend national boundaries in terms of the means by which they are accomplished, the persons they appear intended to coerce or intimidate, or the locale in which their perpetrators operate or seek asylum. (50 U.S.C. § 1801(c))"

"Separatism : During much of the 20th century, the term terrorism was primarily applied to nationalist movements of various types. Most of them were separatist movements, seeking to create a new independent nation-state on the territory of a larger, existing state."

And lastly the word "treason"
"1. Violation of allegiance toward one's country or sovereign, especially the betrayal of one's country by waging war against it or by consciously and purposely acting to aid its enemies.
2. A betrayal of trust or confidence.
Article III, Section 3, of the federal Constitution sets forth the definition of treason in the United States. Any person who levies war against the United States or adheres to its enemies by giving them aid and comfort has committed treason within the meaning of the Constitution. The term aid and comfort refers to any act that manifests a betrayal of allegiance to the United States, such as furnishing enemies with arms, troops, transportation, shelter, or classified information. If a subversive act has any tendency to weaken the power of the United States to attack or resist its enemies, aid and comfort has been given." (No, we cannot call Mexico our "enemy", but the invasion of its illegal immigrants has had the tendency to weaken and divide our country).

"The Treason Clause applies only to disloyal acts committed during times of war. Acts of disloyalty during peacetime are not considered treasonous under the Constitution." (How fortunate for the politicians who espouse amnesty).