ABC News April 17, 2019

A Mueller report guide to collusion: What is it and what could we still learn?

WATCH: Democrats blast Barr over rollout of Mueller report

As Washington anxiously awaits the Thursday release of the redacted version of special counsel Robert Mueller's report, some questions surrounding specific, publicly-reported instances of then-candidate Donald Trump’s campaign contacts with Russians remain unresolved.

Attorney General William Barr, in his letter to Congress last month describing the report’s "principal conclusions," wrote that the special counsel "did not find that the Trump campaign or anyone associated with it conspired" with Russians to influence the outcome of the 2016 presidential election. The special counsel’s office investigated whether anyone working for or associated with the Trump campaign coordinated with Russians in their crimes related to the 2016 presidential election, crimes that included computer hacking conspiracy and conspiracy to defraud the United States, among other things.

(MORE: Democrats slam Justice Department over Mueller report release)

President Trump lauded the news, sparing no occasion to repeat one of his marquee phrases: "No collusion!"

"As far as I'm concerned, I don't care about the Mueller report," Trump told reporters at the White House last week. "I've been totally exonerated. No collusion, no obstruction."

As members of President Trump’s legal team have repeatedly pointed out, the word "collusion," itself, does not appear in the federal code.

Evan Vucci/AP, FILE
President Donald Trump delivers remarks during an event in the Roosevelt Room of the White House, April 12, 2019.
(MORE: Trump says he may hold news conference after Mueller report release)

The non-legal term, however, defined by Merriam-Webster’s dictionary as, "a secret agreement or cooperation especially for an illegal or deceitful purpose," has come to be used as a shorthand for the type of federal crime of conspiracy – which occurs when "two or more persons conspire either to commit any offense against the United States," according to the legal statute.

(MORE: Senate releases insider accounts of Trump Tower meeting between campaign aides and Russian emissaries)

And, the top Democrat on the House Intelligence Committee, Adam Schiff, in response to a question from ABC News Congressional Correspondent Mary Bruce on whether he accepts the special counsel’s conclusion that "[T]he investigation did not establish that members of the Trump Campaign conspired or coordinated with the Russian government in its election interference activities," he maintained "there are a lot of open questions."

"Why did the Russians offer dirt on Hillary Clinton? Why did the president's son say that he would love that help? Why did they set up a meeting at Trump Tower?" Schiff said shortly after Barr issued his four-page memo on the investigation’s findings in late March.

(MORE: Prosecutor: Manafort meeting with Russian at heart of probe)

"These questions have not been answered by the summary we got from Bill Barr," Shiff added. "I would hope that there are answers in the Mueller report."

Pablo Martinez Monsivais/AP, FILE
Paul Manafort, President Donald Trump's former campaign chairman, leaves the federal courthouse in Washington D.C., Feb. 14, 2018.

Areas of interest

Of primary interest to Democratic critics is the infamous June 9, 2016, Trump Tower meeting, referenced by Schiff, between senior members of the Trump campaign and Russians who were expected to offer some dirt on Hillary Clinton.

Another area of interest is the Aug. 2, 2016, meeting in New York between then-Trump campaign chairman Paul Manafort and his former business associate, Konstantin Kilimnik, who has been described by Mueller prosecutors as a former Russian intelligence officer. Prosecutors have accused Manafort of providing Kilimnik internal polling data from the Trump campaign.

(MORE: Read: Barr's letter to Congress on the Mueller report)

Trump's personal attorney Rudy Giuliani said on CNN's "Cuomo Prime Time" earlier this year that Manafort's sharing of the polling data with Kilimnik was not collusion.

"It's not collusion. Polling data is given to everybody. He shouldn't have given to them. It's wrong to give it to them," Giuliani said. "[Trump] did not know about it until it was revealed a few weeks ago in an article."

Questions about Roger Stone and WikiLeaks

In its latest indictment, the special counsel's office detailed former Trump campaign adviser Roger Stone's apparent overtures to WikiLeaks -- on how the veteran Republican operative instructed his associate Jerome Corsi to "Get to Assange," as part of a multi-day email exchange, noting that WikiLeaks was preparing to release emails that "deal with [the Clinton] Foundation, allegedly."

(MORE: Robert Mueller appears laser-focused on Roger Stone. These emails explain why.)

Regardless of whether these incidents raise ethical or moral questions, the matter of legality for the special counsel’s investigation was put to rest when Barr announced in March that the special counsel would not recommend any additional indictments.